Alright - fixed and uploaded the HTML5 version of the game! It's running smoothly! Give the game a shot!

A note to GameMaker: Studio (1.4) users - this is apparently a thing for the HTML5 version: https://www.reddit.com/r/gamemaker/comments/4u3rn0/lessonsinhtml5/

instance_find works differently for HTML5 and other platforms, since the destruction list is updated differently (affects other destruction code too). Just a heads up for future projects - since that might be the reason your game's working unexpectedly in HTML5.