Games

I think it's really impressive what the community has done with Super Smash Bros. Brawl. Project+ is basically the current "flagship" modpack. It builds on Legacy TE (which is built off Project M), so there's loads of new content and more Melee-like gameplay.

Another Brawl mod I like is Brawl -. Its main thing is that it balances the game by making everyone's movesets overpowered.

Changing genre completely, I really like the Gay Awakening and Gay Fates mods for Fire Emblem: Awakening and Fire Emblem: Fates. The main thing the mods do is add new romantic and platonic supports to the game. The focus is, as the name implies, on adding gay and lesbian content, but it also adds straight content to a lesser degree (like for the characters that can only support with Robin or Corrin).

Star Trek Armada 3 for Sins of a Solar Empire. Can't wait for STA4 for SoaSE2.

Minecraft - mouse tweaks, Alex's Mobs, The Bumblezone
Morrowind - I forget what it's called, but the one that adds the mainland
Risk of Rain 2 - any character by Enforcergang. Especially classic sniper and rocket

for Minecraft, the fabulously optimized modpack. gives me over 5x the fps, meaning I can make the game look fancier with higher settings

You know, I actually think it's the miniblocks datapack for Minecraft. That's the only "mod" that is included in every single world I play in. Every other mod in every other game is kind of optional, but I'll never play Minecraft without miniblocks ever again. Not that I use them a ton, but they singlehandedly managed to actually get me exceited for the wandering trader again!

This is going to be a callback, but Ballistic Weapons for UT2004. It completely overhauled the gunplay in ways I’ve never seen replicated. I loved all the extra modes the weapons had and many took a while to learn how to use.

The devs went on to make Viscera Cleanup Detail, so good for them, but I did always wish they made a FPS.

definitely dremor and close second is shitpostpolice. oh boy my lips are so tired.

Antistazi for Arma 3

Any mod that allows me to play as Amy Rose in any Sonic game.