This is where all the Gameplay stuff happens and is managed
here's some useful tips if you are making a mod in source:
If you want to add your stage to the game, copy states/stages/Template.hx, and put your stage code there, then, on PlayState, search for "switch (curStage)", and add your stage to that list.
If you want to code Events, you can either code it on a Stage file or on PlayState, if you're doing the latter, search for:
"function eventPushed" - Only called one time when the game loads, use it for precaching events that use the same assets, no matter the values "function eventPushedUnique" - Called one time per event, use it for precaching events that uses different assets based on its values "function eventEarlyTrigger" - Used for making your event start a few MILLISECONDS earlier "function triggerEvent" - Called when the song hits your event's timestamp, this is probably what you were looking for