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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 Information

This game does not collect personal information.

Two situations may prompt you for additional access:

  1. If you are playing music from another app and enable the game’s Auto-“Next” feature, the game will ask the OS to switch to the next song in your playlist whenever there is a key game event (new stage or boss fight).  Otherwise the game does not access your Music.
  2. The OS may ask for permission to help developers improve their apps.  If you allow this, the OS vendor may choose to inform the developer of this game about problems (for example, if the game unexpectedly quits).

Game Setup: Performance

Celtreos tries to set a reasonable quality level automatically.  If you find the game is still not performing well, you can specify the quality level (below).

In addition, note that sound effects have a small but nonzero drag on the game; playing with sound completely “off” may help on slower hardware.  (Music is OK.)

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 (version 1.4 and later), 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.

Game Setup: 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

Game Setup: Controllers

Game controllers can be used to play the game and interact with the user interface.  The exact method to connect 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 (for example, not all buttons may work).  It is recommended that you connect and turn on your controllers before running the game, just in case.  If you can move the cursor and tap interface elements using the A button, the controller should be fine in the game as well.

Use the game controller category on the main options screen to select a controller if you have more than one, and to see how the controller maps to actions in the game.

If you have one game controller connected in a two-player game, it should already be automatically assigned to the second player (assuming that the first player will use the device’s native input: mouse for Mac, touch screen for iOS).  In a one-player game, the controller should be automatically enabled.  And if you connect two controllers in a two-player game, each player should automatically be assigned a different one.  (You can change any controller assignments before the game begins; if you connect a controller while the game is running though, only the default assignment will be in effect until you end the game.)

IMPORTANT:  Game controllers have a different “feel” than keyboard or mouse or trackpad or touch controls.  Remember that the A button can be held down during gameplay to slow down, which can help to adjust to the different response of the directional controls.

When a game controller is available, the “focused” user interface element will have an animated arrow with a label for the A button, which means that pressing the A button will activate the focused element.  Use the D-pad or left analog stick to change focus.  In some cases, interface elements have more short-cuts annotated (such as L1 and R1 to change option categories on the Mac).  Touch and keyboard controls continue to work while game controllers are connected.

Game Setup: Players

In version 1.30 or later, Celtreos is a multi-player game!

Once you enable a two-player game, the “PLAYER SHIPS” and “CONTROLLER SETUP” 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, and you can give each player a different game controller (although the game’s default game controller assignments are usually fine).

The game does change slightly when there are two players (and future versions of the game may tweak this further!).  For instance, bosses are harder to kill unless you work together!  Only one weapon array can be set at the start of the game but each player may end up with different subsets of the available weapons and defenses: power-ups and power-downs only apply to the player that touches them.

In order to scroll around the screen (see Movement), players must agree on the direction to go.

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.

Game 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 iTunes; on iOS it is supported for anything that can be played by standard system audio controls.

Game Setup: Other

You can specify the number of Lives (how many times your ship can be destroyed before it’s Game Over), the number of Charges (how many times you can use wide-area attacks), the shape/size of your ship, and the weapons that will spawn in the game.  In multi-player games, you can assign each player to a different type of ship but other settings apply to both players equally.

For convenience on iOS, some of these are also available in a limited form via the Settings app (under “Celtreos”).

Pausing or Quitting

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.


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 on the Mac can be specified in the Celtreos application menu).  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).  In version 1.30 or later, 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.

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 (version 1.31 or later).  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.  (Note: Prior to version 1.27, the option key was used to toggle ship speed.)


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.

Regular Weapons: Firing

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.

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

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.

Regular Weapons: Switching

Although you select an entire weapon array at the start of the 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 (in version 1.30 or later) 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, and “5” for the highest-powered weapon.  In version 1.22 or later, 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 and the “Weaver Series” (version 1.28 or later) has Time Warp.

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.


Enemy attacks will usually destroy your ship instantly but there are a few kinds of defenses available (depending on the weapon array specified at the start of the game).  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:


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

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 (version 1.26 or later)
  • Temporarily speed up weapons (version 1.31 or later)
  • Reduction in power of main gun (“–”)
  • Unable to switch weapons (padlock icon)
  • Briefly slow down weapons (version 1.31 or later)

More items will appear in future versions of the game!


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!


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.


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.


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.