Yeah Nice idea By the way

Funnily enough, thats exactly what Lego Star Wars: Episode 3 is.

A Way Out is similar

Double Dragon is the game you are looking for.

Than the win gets all the losers stuff and the loser has to start all over again.

It'd have more than that. It should be a game that requires two people to play it together in order to advance. You can only level up if your partner lets you but you can't move through the game if you don't level up. You score higher and you get better perks by helping your partner do better. Encourage selflessness by giving better stat bonuses or stacking affects when you give your partner gear that's better than your own. Tough bosses all the way to the end where you have to fight each other. Whoever wins gets to keep the gear but only the gear they gave to the other player.