How I make that silly fighting game and the possibility of making mods
Hi, the reason why you did not get any reply so far is that you are basically asking how to make an entire game. It is quite unlikely that someone is starting to post all the events that you need.
I would suggest that you identify all the mechanics that you need for making the game, try to implement one after another and if you get stuck you could ask about this one problem here in the forum.
Not useful at all your response
@Drona’s response is correct. You need to identify or break down the game into its core mechanics and components, and work on those. Things like player movement, fight actions, collision when fighting etc. Get one working, then do the other.
As for mods, what kind are you after? Scene extension? New characters? Playing character accessories? Unless you can update these with metadata, it’d probably require a game rebuild and release.
Note, this forum is not to request how to make a complete game. It’s for asking for help when you get stuck while making a game with GDevelop.