Nuclear Throne Together allows to define custom mutations.

These have .skill.gml extension.

The following scripts can be defined for them to be called by the game:

init

Executed when mutation mod is loaded. Load resources here.

game_start

Executed when game is starting. Reset any global variables here.

step

Executed every step after/while mutation is taken.

skill_name

Should return mutation name (will default to filename).

skill_text

Should return mutation description (will default to "?").

skill_icon

Should return a sprite for HUD' mutation icon.

skill_button

Executed for skill button when it appears. Should setup it's sprite.

skill_avail

May return whether the mutation should show up in pool.

skill_take

Executed when the mutation is picked.

skill_lose

Executed when the mutation is lost (removed via skill_set).

skill_wepspec

May return whether the mutation is weapon-specific (adds up towards Heavy Heart).

skill_tip

Can return the skill-specific loading screen tip.