Unbeatables

Fallout Shelter

Its a Fallout-themed management game, in which you manage your own Vault. You have three main resources you must keep an eye on, vault dwellers that you have to keep happy and geared (for protection, in case if there's a raid or accident with radscorpions coming out of the room's floor) and the bottle caps that you have to spend for expansion. You can also task your vault dwellers to explore the wastelands or do some silly quests.

Its a nice time killer, if you happen to be bored when waiting for something. While I've played the game on my phone, there's a PC version too, not sure why though.

Garry's Mod

The game is a sandbox, based on Half-Life 2, where you can take some props, build something ridiculous or kill some NPCs in dumb ways. There's also a multiplayer with a lot of roleplaying servers, as well as zombie mode, hide-and-seek and cinema servers.

If you'll get bored from using the same guns, the same NPCs or you want to do something else in GMod, there's a Workshop, where you can find the addons you want, you can even turn your Half-Life 2 into Dishonored with some addons. People have also used GMod to create posters or short and funny movies too.

Mount & Blade: Warband

The game is a sandbox RPG that takes place in the fictional continent of Calradia during medieval times. You start by creating your character and finishing the tutorial missions. Now you're on your own, you can roleplay as a merchant, raid villages, start your own army and either join one of the factions or make your own. Just do whatever you feel right. The combat is kinda janky, but its fine, though you shouldn't rely solely on yourself, even just a few troops can overwhelm you. The music in the game is nice and memorable. The only thing that annoys me is the repetition, but I guess it should be expected from sandboxes.

The game also has a modding support, which lets you to transform your game into a fantasy game based on Mount & Blade itself, Lord of the Rings, Game of Thrones, or even based on real history, like feudal Japan, Roman Empire or Jerusalem.

Stardew Valley

Its a cutesy farming sim, heavily inspired by Harvest Moon (the game started as a successor of Harvest Moon, since the franchise started become a cashgrab). You play as an office clerk, you got fed up with your boring job, so you open the letter from your grandpa that has passed away and inherit the farm he had. Now its up to you to start your own farm.

Besides farming, you can also visit the locals, help them out with some errands or even date some. The game doesn't really have an end though, so you can stay as much as you want and keep your farm nice and tidy.

The Sims 3

Its a life simulator with some supernatural and futuristic elements. Besides playing as yourself or roleplaying as someone else, you can also edit the town however you want, you can build your own houses, make your own sims and put them in the world. Or if you have enough will, make your own with some tools available for the game.

While people say that stock The Sims 3 has enough content, I think you should get all the expansions (except for one that was licensed and nobody cares about). But please, buy the game when it costs $190 (or less, if you're lucky). Or "sail to The Seven Seas", if your country doesn't care about piracy and/or if you hate the fact that EA got sold to Saudis, but be careful, websites like The Pirate Bay shouldn't be trusted at all (and its not a joke, avoid that website at all).

Tuna Hake's Underwater

Its a small silly game, where you play as a fish and do tricks Tony Hawks style with some nice music in the background and unlock more fish. Thats it. The game is cheap and it feels like one of those games you could've had in your childhood and fondly remember. Also yours truly (credited as u/WhiteRedBirb) contributed to this game a bit by suggesting a few things that should be added or changed, not much, but I wanted to see this game in a more polished state.

WEBFISHING

Its a chatroom game, disguised as a cute and silly fishing sim. You can catch the fish, upgrade your tools and baits, get some better clothes, scribble some dumb things with chalk, play on guitar and talk to people. If you want to play the game, you should install a Calico mod first for performance boost. The game will lag without it.