While you're here, please consider supporting GamingOnLinux on:
Reward Tiers:
Patreon. Plain Donations: 
PayPal.
This ensures all of our main content remains totally free for everyone! Patreon supporters can also remove all adverts and sponsors! Supporting us helps bring good, fresh content. Without your continued support, we simply could not continue!
You can find even more ways to support us on this dedicated page any time. If you already are, thank you!
Reward Tiers:
Patreon. Plain Donations: PayPal.This ensures all of our main content remains totally free for everyone! Patreon supporters can also remove all adverts and sponsors! Supporting us helps bring good, fresh content. Without your continued support, we simply could not continue!
You can find even more ways to support us on this dedicated page any time. If you already are, thank you!
Login / Register
~/.config/unity3d - locations of basically all save games from the Unity Engine (Wasteland 2, Gone Home, Among the Sleep, Rust, Kerbal Space Program, probably a several others)
~/.config - has odds and ends for other games (FEZ, Wasteland2, some Mono settings, etc)
~/.local/share - locations of most saves for games without a big-name engine behind them (CaveStory+, FEZ, TowerFall, Rogue Legacy, Gunpoint, Dungeons of Dredmor, probably others). I also see some files for UDK games in here (Sanctum2, Antichamber)
~/.local/share/Steam - a lot of things, most of which are automatically generated, but I believe /userdata/<userID>/<appID> has save data for some games, and /SteamApps/common/<Game> has save data for Valve games
~/.minecraft/saves - Minecraft worlds
If you know of any default save locations I missed here, post'em - it's frustrating to only find locations for Windows when googling this stuff.