The Binding of Isaac: Rebirth (plus DLCs): Nothing else comes close to the item variety and more importantly the item combinations and synergies you get in this game. Sure, there are a bunch of items that are just stat boosts, many other games stack these. But in Isaac you also get stacking and synergies on weird weapon and item effects that can sometimes lead to almost game breaking outcomes. And then you still manage to die.

Because of this Isaac excels at the “just one more run” style replayability.