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Celtreos is available for macOS and iOS.


Before asking questions, PLEASE read the information below.  You may E-mail me about the game but use “Celtreos” as a subject line to help speed responses.

 ⌃   Privacy Info

This game does not collect personal information.

Music Access:  When you have music playing in another app, you can choose to enable the Auto-“Next” feature in Celtreos; if you do, the OS may ask for approval to access your music.  This permission is only used to switch your player to the next song in the playlist for key game events.

 ⌃   Performance

Celtreos tries to set a reasonable quality level automatically.

There are some settings that can improve performance (at the cost of quality):

To change “Graphics Quality”:

In the Settings app, under “Celtreos”, go to “Graphics Quality”.  You may need to force-kill and restart the Celtreos app for this change to fully take effect.
On the Mac, use the Celtreos application menu to set the quality setting.  You may need to quit and restart the Celtreos app for this change to fully take effect.

 ⌃   Recovery Mode

Normally, if the app is killed in the middle of a stage, the game will resume at the beginning of the stage with your weapons, score and other attributes intact.

If the app has trouble resuming, you can force it to return to the title screen (if you do, the setting turns itself off after the next launch).

In the Settings app, under “Celtreos”, toggle on “Force New Game at Start”.
On the Mac, a terminal command shell must be used (all on one line):
defaults write name.kevingrant.celtreosmac doNotRestoreState -int 1

 ⌃   Controllers

Celtreos should work with many game controllers, including those supporting “MFi” and (in more recent macOS versions) PlayStation and Xbox controllers.  If you have issues with any particular controller that works with other games on Apple systems, please see Support above and be specific about the issues you see.

The exact method to connect a controller may vary; for instance, Bluetooth controllers on a Mac can be set up using the Bluetooth panel in System Preferences but iOS uses Control Center or Settings.

IMPORTANT:  Some hardware does not respond correctly if it is plugged in while the game is already running; try to connect before opening the app.

On the main options screen there is a category for game controller setup, where you can assign controllers (for multi-player games) and learn what all the buttons will do.  Note you can also use the ship editor to lower the maximum speed of your ship, which can help significantly when using a game controller.

 ⌃   Setup: Players

Once you enable a two-player game, certain options screens and ship-editing screens will have “Edit P1” and “Edit P2” buttons at the top to let you configure each player differently.  Currently you may give each player a different ship Model, gun mount and top speed, and you can specify each player’s game controller.

The game does change slightly when there are two players.  For instance, bosses are harder to kill unless you work together!  Only one weapon array can be set at a time but each player can have a different subset of available weapons and defenses.  Power-ups only apply to the player that touches them.

In order to scroll the screen vertically (see Movement), both players must agree.

Since there is no alternative interface built-in to phones or iPads, a game controller is required to play with someone else.  Select “2P” on the main option screen (iPhone) or “2” in the Players category (iPad) for a two-player game; then use the game controller screen if necessary to reassign the controller.  The touch screen always controls the first player but if you have two controllers you can still assign one to the first player.
Select “2” in the Players category.  On the Mac, the 2nd player is automatically reassigned to use the keyboard (and the first player uses the mouse) but you can assign a game controller to one or both players.  Note that this is different than one-player mode, where the mouse and keyboard will both affect the player.

 ⌃   Setup: Ships

Ship and weapon configuration options are a separate screen, and this also provides access to a “test stage”!

The Model defines the appearance of the ship but also its size (larger ships will be harder to navigate in narrow areas), and to some extent the spacing of guns.  You can further customize guns using the Gun Mount (for example, arranging attacks above and below the ship, or even circling around it!).

You always have a choice of two ship speeds but you can configure the highest speed in this editor.  When using a game controller or keyboard, lowering the top speed will generally make maneuvering easier.

A Test… can be launched to safely try out your current weapon arrangement, in a simulator against endless targets.  This is also a good way to test the effects of power-ups such as multipliers, and it lets you easily enable several defender pods at once.

Note in multi-player games, you can assign each player a distinct ship model, gun mount, and top speed.  The array of weapons and defenses must be shared however.

 ⌃   Setup: Music

Music and sound controls are available both at the start of the game and during gameplay (via the pause screen).  This allows you to change the volume and the music track at any time.

If you have music playing in another app, Celtreos can use it!  Regular game music is automatically muted and a new option appears in music panels for “Auto Next-Song”: when selected, key game events (boss fights and new stages) will cause your music player to switch to its next song.  Note that on the Mac this feature is only supported for the iTunes/Music app; on iOS it is supported for anything that can be played by standard system audio controls.

 ⌃   Setup: Other

You can specify the number of Lives (how many times your ship can be destroyed before it’s Game Over) and the number of Charges (how many times you can use wide-area attacks).

In version 1.69 and later, you can set additional game preferences!  The “Don’t switch to new weapons” setting will keep your current weapon whenever you collect a weapon power-up, instead of automatically changing your current weapon.  And the “Keep weapons after death” setting makes the game easier by letting you keep all your weapons after you die, instead of losing them; note that the Preserver power-up does not spawn in this mode.

Preferences can be set as follows:

The Settings app (under “Celtreos”) can be used to tweak these settings; and if you have an iPad, they are also available on the main options screen in-game (similar to the Mac version).  Note that on a small screen, some settings are only available in the Settings app.
Set the on/off switch next to each setting in the main options screen.

 ⌃   Pause or Quit

To temporarily pause gameplay on any platform, you can switch to another application or use one of the methods below.  While the Paused screen is showing, you can leave the game (returning to the options screen), change music and sound settings, and enter a special mode to make it easier to take screenshots.

If you have a game controller, use the pause button on your controller; this may be called MENU or have a different icon.  The same button can be used to resume the game.  Once paused, you can use the controller to navigate through the onscreen interface with the D-pad and press the A button to activate the action that the animating arrow is pointing to.

Press the interface element with two vertical bars at the bottom of the screen to pause the game (the game is also paused if you open a weapon selection menu or perform any system task on iOS such as responding to a message).  Resume the game using the interface elements that appear onscreen; note that an action with a “slide” animation must be activated by sliding your finger across the title of that element.
Press the command key (⌘) and type period (“.”) to pause the game; or, hold down the command key to “free” the mouse pointer and select “Pause or Resume Game” from the Celtreos application menu in the menu bar.  Resume the game using this same sequence, or by clicking an interface element that appears onscreen.  If your Mac has a Touch Bar, you may also use that.

 ⌃   Movement

On the Mac, a Keyboard and Mouse panel on the main options screen describes how movement works with those inputs.  You may also connect a game controller and use the D-pad or left analog stick.

Your ship normally moves continuously at its base rate of speed (which can be changed using Top Speed options).  In stages with walls, the default speed will be automatically slowed to make obstacles easier to move around.  Regardless of the base speed, you can further reduce speed by activating Slow mode; see below.

You can move quickly toward any location by clicking/tapping that point.  While jumps can be quite efficient and strategic, be careful: you will go straight toward anything in the way, including walls that destroy your ship!

The game world is more than one “screen” high, and moving toward the top or bottom edges of the display will scroll automatically.  Sometimes you can only find certain items by moving around!  Also, boss battles rely heavily on being able to move freely over a wide area.  In multi-player games, the screen scrolls only based on the average location of both players so you must “agree” to scroll far in one direction or the other.

If you have a game controller, holding down the A button will slow down your ship as you move with the D-pad or analog stick (and releasing the A button will return to normal speed).  You can use the X button to toggle the default speed (fast or slow) and then the A button will temporarily switch to the opposite speed.

Note that opposing-movement weapons (such as “Sweeper” or “Star Strike”) will change direction whenever you move, to fire in generally the opposite direction.

Hold your thumb or finger down and move continuously to fly your ship around.  Tap the screen to jump straight toward that spot.  To activate Slow mode, tap the Slow button in the top-right corner of the screen; tap the button again to turn off Slow mode.  (In multi-player games, only one player will be affected by touch screen controls and the other must use a game controller.)
Move the mouse to fly your ship around.  Hold the mouse button down and drag the mouse or trackpad to toggle ship speed until the mouse button is released.  Hold down the command key (⌘) to “free” the mouse pointer (temporarily keeping your ship from moving), then move the mouse to another location on the screen and click to jump straight toward that spot.  Equivalent actions on a trackpad may also be used.  Use the caps lock key (⇪) to toggle the default speed (fast or slow).  Hold down the shift key (⇧) to temporarily switch to the opposite speed while you use the mouse or direction keys, releasing the key to return to the original speed.  If Slow speed is active, an icon will appear next to the player score.

 ⌃   Obstacles

Certain things in the game will instantly destroy your ship regardless of any shielding!  Obstacles include: the first boss ship, very large asteroids, walls, and sliding hatch doors.  (In general, if it looks dangerous, it is!)

In addition, flaming exhaust and bombs will destroy your ship unless you have defenses with sufficient strength.

 ⌃   Weapon Fire

Weapons will fire automatically when you move your ship.  If you really want to stop firing, you can take a specific action to do so (below).

The only weapon you always have is a main gun.  It takes awhile to charge so you need to stay alive continuously to reach the maximum strength or obtain “+” power-ups to grow faster.

As a matter of balance, weapons that can “follow” enemies may also go for things you don’t want them to see, including enemy laser fire (impossible to destroy) and some extremely-well-defended spots on enemy ships.  You may find in a dense firefight that you need to switch to a more controlled weapon.

Lift your finger to stop firing.
Click the left mouse button, tap the trackpad once or hit the space bar to stop firing.

 ⌃   Weapon Aim

Most weapons can be used effectively just by lining up your ship with a target.  Some weapons, such as Seeker, also require you to be close enough.

A few weapons have the ability to bounce off of solid targets, such as walls or even parts of boss ships.  You can use this to your advantage, continuing to damage enemies after a deflection.

Though rare, certain weapons have the ability to go through obstacles that would stop other weapons.

Note that opposing-movement weapons (such as “Sweeper” or “Star Strike”) will fire in the opposite direction that you most recently moved.  You can only aim these in a different direction by moving your ship somewhere else.  Keep this in mind when your ship is in a tight spot because you may not be able to easily fire where you want to!

 ⌃   Weapon Switch

Although an entire array of weapons is available in-game, you may only use weapons that you have found power-ups for.  In addition, if your ship is destroyed, your weapons are scattered and you may not be able to get them all back!

When you obtain a weapon power-up, you switch immediately (even if it is considered weaker than your previous weapon!).

You may manually switch to any weapons in your possession, as shown below.

If you have a game controller, the shoulder buttons L1 and R1 will rotate through your current weapons and the Y button can be used to switch back to your most recent weapon.

The interface element in the bottom-right corner displays the current weapon and is used to switch weapons.  If you have exactly two weapons, a single tap will swap to the other weapon; otherwise the button has up-arrows to indicate that a menu will open.  (On iOS devices with 3D Touch, you can press “in” on the button as a short-cut to rotate weapons without displaying a menu first.)  Note that this button can be tapped at the same time that you control your ship with the other hand.  (In multi-player games, only one player will be affected by touch screen controls and the other must use a game controller.)
Click the right mouse button or hit the “Q” key to switch to another weapon that you previously obtained from a power-up.  (Currently, these mappings cannot be changed.)  If your Mac has a Touch Bar, you may also use that.  You can also use number keys to directly switch to particular weapons: “1” for Default, “2” for the multi-way weapon in your array, “3” for the vertical weapon in your array, “4” for the locator-class weapon, “5” for the highest-powered weapon, and “6” for the opposing-movement weapon.  You can use the “R” key to go back to your most recent weapon, and again to toggle back and forth between the last two weapons.

 ⌃   Area Attacks

An area attack can easily damage or destroy several targets on the screen at once, and it is not affected by walls or other obstacles.

Different weapon arrays have different area effects.  The “Blaster Series” has a Bomb attack, the “Razor Series” has Lightning, the “Plasma Series” has Ray Burst, the “Weaver Series” has Time Warp, and the “Devastator Series” (version 1.63 or later) has Concentrator.

The number of “Charges” you set at the start of the game determines how often you may use area attacks.  In addition, there is a multi-second cooldown period.

It is possible to gain a Charge from a special power-up.

Like your Lives, the number of Charges applies to the entire game (all stages), not expiring even if you lose other weapons.

If you have a game controller, the B button unleashes an area attack.

If the first player has any charges remaining, the interface element 2nd from the right on the bottom of the screen will display the number of charges left, and can be tapped to unleash an area attack for that player.  (This icon will also show a flashing “X” until the cooldown ends.)  Note that this can be tapped at the same time that you control your ship with the other hand.  In multi-player games, there is no on-screen button for the 2nd player but the number of charges briefly appears when activated via the second player’s game controller.
Click the middle mouse button, double-click the primary mouse button or hit the “B” key to unleash an area attack.  (Currently, these mappings cannot be changed.)  If your Mac has a Touch Bar, you may also use that.  Note that in multi-player games, the keyboard will be assigned to the 2nd player so the 1st player must either use mouse actions or connect a game controller.

 ⌃   Defenses

Enemy attacks will usually destroy your ship instantly but there are a few kinds of defenses available (depending on the weapon array that is in use).  They are obtained through power-ups.

Pods extend your ship’s offensive capabilities to cover a larger area, and you can obtain more than one at a time:

Guards have vulnerabilities, meaning that they may not last forever even if you stay alive:

 ⌃   Items

The game spawns spinning orbs that can have both beneficial and detrimental effects (distinguished by appearance).

Each stage has exactly three fragments (gold icons with a “?”), that only have value if you find ALL of them!  If you do find all 3 fragments in the current stage, a massive number of power-ups will spawn as a reward!

At the end of each boss fight it is possible for up to three weapon array power-ups to appear on the right-hand side of the screen.  If you pick up one of these, all available weapon power-ups will change from that point onward.  Also, any weapons you currently possess will change to their equivalents in the new set; for example, if you have the locator-class weapon “Seeker” and you switch to an array that has the locator-class weapon “Phaser”, your “Seeker” will be replaced with “Phaser”.  As before, in two-player games, both players share the same set of available weapons: if either player changes the current weapon array, both players will be affected.

Pick up an item by touching it with your ship.  Items fade away so you need to be quick!

Items are usually randomized in some way, such as movement speed and location.  It is also possible that the type of an item changes from one game to the next.

If your ship is destroyed, there is a chance that power-ups will spawn.  Sometimes, every weapon you had will be scattered across the game field.  If you’re really lucky, you may see special items.  It is also possible that nothing will appear!

  • Extra life (“1”)
  • Extra charge (varies based on weapon array)
  • Increase in power of main gun (“+”)
  • New weapon (varies)
  • New defense (varies based on weapon array)
  • Score bonuses (“500”, “10000”)
  • Preserve last weapon after loss of ship (this does not spawn if “Keep weapons after death” is in effect)
  • Temporarily speed up weapons
  • Temporarily shoot twice as many projectiles
  • Temporarily shoot three times as many projectiles
  • New weapon array (varies; available at end of stage only)
  • Reduction in power of main gun (“–”)
  • Unable to switch weapons (padlock icon)
  • Briefly slow down weapons
  • Lose current weapon
  • Decrease of weapon range

 ⌃   Achievements

You can gain several seconds of invincibility by meeting the conditions for an Achievement, which usually means completing some difficult or impressive task.  While your Achievement’s “trophy” is on the screen, your ship is invulnerable to any attack and your ship can also pass through walls or other things that would normally be fatal!

Each player can score each type of Achievement only once per game, even if the conditions are met again at a later time.

Achievements aren’t listed anywhere; you must figure out how to activate them yourself!

Once you figure out how to trigger some Achievements, you may want to be strategic about when to use them in future games.  For example, if you are close to a boss fight and you are close to fulfilling the requirements for an Achievement, try to wait so that it triggers at just the right time!

 ⌃   Stages

You may select any starting stage from the options screen but you must play every stage in a single run to see the game ending.  (If you finish the final stage but did not start from Stage 1, you will rotate back to Stage 1 to play the remaining stages.)

Bonus points accumulate after each stage if you hit lots of targets or finish in a reasonable amount of time.  The maximum bonus for each of these is 50,000 points.  In multi-player games, each player will have the same time bonus but a unique shooting bonus!

Most stages are not exactly the same every time you play them, and some can be radically different!  Look out for changes to walls, enemy spawns, power-ups and more.

Stages also have different environmental effects that change weapons and other parts of the game.  For instance, space has no gravity, no fire, and reduced sound.

 ⌃   Enemy Attacks

Round, orange enemy bullets and smoking enemy missiles can be destroyed if you fire at them enough.  No other enemy attacks can be destroyed by ordinary weapons.

Large explosions can be useful!  Note that unleashing an Area Attack or even destroying certain enemies will eliminate all enemy weapons fire on the screen instantly, including things that are not normally destroyed (like lasers).

Attacks will instantly destroy your ship unless you have defenses.

 ⌃   Bosses

Every stage ends with a “boss” fight, announced by a change in music and a WARNING prompt.

In multi-player games, bosses are significantly stronger and you must work together to defeat them in a reasonable amount of time!

Most bosses can collide with your ship, making them as dangerous as walls!  They may also move in ways that limit your escape so you need to plan ahead.  Remember that your ship can switch to a slower speed.

Destroy the parts of a boss, like turrets, to make the fight easier.  Attacks will often remain focused on your ship’s previous position for a short time, creating an opening for a counterattack to destroy a turret.

Find the best weapon for each situation.  Many weapons are stopped by boss attacks.  Not all target points on a boss are equally vulnerable but auto-locating weapons will be drawn to every nearby point.  Bosses frequently protect themselves with shields and some weapons are better at penetrating shields than others.  Once you eliminate a shield, be quick because the shield might regenerate!

Sometimes your main gun really is the best weapon for the boss.  The main gun powers up automatically over time so even if you have lots of Lives to spare, it pays to avoid attacks and gain strength.

Time bonuses at the end of the stage can be significant.  Boss fights will be a lot quicker if you are able to retain weapons and defenses from earlier in the stage.  Also, some attack points on a boss (like turrets) do not count toward the total health of the boss and it may be faster to ignore them.

 ⌃   Screenshots

To hide the game’s display elements for better screenshots, pause the game and select the camera icon.  After a few seconds the display will return to normal; in the meantime, take a screenshot in the normal way for your device.