It could be like a deck builder where decks rotate or you pick combos of characters/decks. Fewer mechanics for more combos. I'm inspired by cobolt core and slay the spire. https://play.google.com/store/apps/details?id=com.ztgame.yyzy&pcampaignid=web_sh... is a game I've purchased and it uses different characters and branching progression to make it highly replayable while reusing the core mechanics.