Risk of Rain 2 and Robo Quest are probably up your ally because you like Ultra kill
But if you want to diversify genre, here are some that I would recommend
Card Games - Slay the Spire (Its like a card game and rogue like combined)
Rogue Like - Hades is currently one of the top tiers in rogue like dungeon crawler
RPG - Baldurs Gate 3, even if you end up finishing the game, how you ended up finishing it is what makes it so replayable. Each character has their own stories for you to uncover. Larian’s other gem is Divinity Original Sin 2 too
Sandbox Games - Minecraft of Terraria
Arcade - Most arcade games are highly replayable because thats their whole selling point. Currently I am back to playing Temptest 4000