Games
Minecraft: Java Edition (Windows/Mac/Linux)
It's good. Later updates are mostly fluff but the game is still enjoyable. I highly recommend using the MultiMC launcher. It supports installing Forge and LiteLoader (and mods) and having multiple self-contained instances (hence the name).
Sanicball (Windows/Mac/Linux)
yeah it's good
SimCity 2000 Network Edition (Windows)
Hey! I have a page on this one! Check it out here!
OpenRCT2 (Windows/Mac/Linux)
It's RollerCoaster Tycoon 2! But it's open source! And it runs on multiple platforms! And it has multiplayer! You'll need the original game to play it, multiplayer tends to disconnect a lot (it has been getting better, though), and setup on Linux in particular can be a little difficult, but it's tons of fun if you liked the original.
Wii Party (Wii)
This game hits the sweet spot for me when it comes party games. Mario Party 6-8 are fun too in my opinion, and Mario Party > 8 has its moments, but Wii Party seems to be my favorite. There are several game modes, including the more traditional Board Game Island, going around the world in 60 minutes, the world's shortest game of Bingo, a game show, and Swap Meet. The minigames are enjoyable and unique.
Wii Music (Wii)
I guess this technically classifies as a "guilty pleasure", but for me anyway, it's a legitimately fun title when you've got some minutes to spare but don't want to go through a full game of Wii Party. Song selection isn't amazing, but you do get some well known ones. Nothing like Rock Band or Guitar Hero, of course, but that's not necessarily the type of crowd this was directed to anyway.