Terraria is the easy pick for me. I believe the only game that comes even close to the amount of hours I have in it would be Minecraft. I doubt I need to say much about this game, so I’ll leave it at 3 words: near infinite replayability.
Melvor Idle is an amazing game if you like the “idle” in idle games. And if you like the idea of leveling up a multitude of different skills like in RuneScape but don’t like the idea of walking back to a town every time you’ve chopped down 12 trees, Melvor Idle has you covered. It’s a long grind but I had fun the whole way. I’ve 100%'d it and all the DLCs and still love playing it.
Cassette Beasts… I’m genuinely surprised I haven’t seen this game mentioned here. An absolutely amazing creature collector with a very unique twist on things, a great story, beautiful pixel art, and hands down the best game soundtrack I’ve ever heard.