Rainbow six siege - advise to watch online or wait until they offer a free weekend as it's relatively expensive however it is fun and a good go to when you're bored
Divinity original sin 2 - In depth RPG with team building. Good on co-op/team. Open play until fights where it's turn based actions. Easily sink hours into it, has replay ability to discover different quests, ways to improve, better fighting or spells etc
Prison architect - Prison building simulation game, easy going and has a low learning curve to begin with
Minecraft - you've probably heard of it, install mod packs to have a questing side of things, or just do your own thing. More fun with friends if you ask me.
Red dead redemption 2 - Possibly the game of 2018? With a good pc you'll see why, excellent attention to detail and a fun game - online mode is not great though
Cooking simulator - You control hands and try to keep up with orders, fun and quirky, frustrating and unforgiving but great. Recipes are always on display bit can get difficult to manage everything going on
Green hell - Survival genre, difficult and no real tutorial so to speak. Learn from your mistakes. Very fun but again unforgiving.
Ancestors - not out yet, similar to Green Hell, survival type game but more evolution based as you're a monkey working upto a human
Football manager 2020 - out in November, if you're into football, manage a team however you don't play the actual football game itself. Can be tricky, huge depth of game. Very customisable and enjoyable, easy to sink hours into
Baldurs gate 3 - Not out yet, been years since a balders gate came out, but the folks at Divinity Original Sin are bringing this one out so could be fantastic
Age of Empires 4 - Again, not out, worth a pre order, of you think you'll enjoy it, recommend buying Age of Empires 2 (best of the set)
Skyrim - Old, memed and glitchy, but one hell of a game. Open world exploration. Many quests, random encounters, be an ass or be a law abiding citizen and kill of the various guilds etc. Magic and melee skill moves. Great views from mountains
Don't Starve - a few iterations of this game, there is a base edition as well as a sea/pirate one as well as an online version. The game is on the name, don't Starve, as well as don't get eaten in the dark etc. Survival game, unique graphics and gameplay. Fun, but again no real tutorial in game. Ramps up in terms of the learning curve the further you go in.
Oxygen not included - From the makers of the above game, similar to don't Starve but this time it's trying to get people to stay alive in side of an area with a lack of oxygen. Unique graphics. Quite fun, big learning curve due to depth of in-game statistics
Call of duty modern warfare (the newest iteration) could be as good as the previously good COD whenever that came out, time will tell.
Dark souls 3 - Never actually played this, however based on what friends have said to me and what I've seen online, it's a very good game. Dubbed one of the hardest games in recent times.
There is a small list of most of my favourite games. I tend to play online with friends now on most games but every now and then I just leave a game on in the background ticking away. I can't recommend Divinity original sin 2 enough though.
Look at YouTubers playing these games, however I'd maybe watch 3/4 different people playing as some people give games a bad review/bad look by their way of playing - I know I do. Obviously it comes down to what you like as well. Try g2a.com to get a slightly lower price on some games however sometimes they are cheaper from original source i.e steam/Ubisoft etc. Let me know if you get any from the list and if you need help with anything
I put some pre orders on there as well because these all look great