There's been some mention of this in the "What are you playing now?" thread but I think it deserves its own as it's a bit notable in its own right and I know there's a few folks playing it.
Valheim is a survival/building game in Early Access on Steam. It's been out there for almost exactly a month, and yesterday it hit 5 million sales, which is just astonishing - it's also up to number 2 on the Steam concurrent players list. The premise of the game is fairly simple - you're a dead Viking who's been tasked by Odin to enter the realm of Valheim, where some big bad guys are hanging around. You gather resources, build weapons, housing, armour, and snacks, and you head out and smite 5 (currently, with more planned) big mythic beasties to defeat which in turn unlock new paths to progress - new crafting materials, or tools that help you to expand your exploration.
The game world is progressively generated and split into biomes that are progressively more dangerous as you explore further away from where you start. More vital resources are found in further away biomes, encouraging exploration and taking risk with tougher enemies but the general pace of the game is pleasantly sedate. You can happily while away hours building things in the starting biome with the only real opponents being mild nuisance creatures and the crafting/building aspect of the game is really well fleshed out - the game happily lets you choose between being an explorer seeking out tough fights for valuable rewards or just someone who builds a nice cottage and grows carrots. Food in the game represents buffs which are super important for health and stamina to let you survive tricky combat, but you'll never starve so there is no desperate need to be constantly grinding for food. The environment is almost fully destructable, making it easy to make use of the land for building and the majority of construction resources you need are easy to come by.
Go play it! It's fun, it's cheap (£15.49), and you can be a super pro Viking dude.