Short version: Very addicting PVE co-op mining FPS game with dwarfs inside space-caves fighting off alien bugs.

Long version: Can be played solo, or up to 4 people together online. There are 4 different classes, namely Gunner, Engineer, Scout and Driller. Each class has a unique way of traversing the various sequentially generated areas in the game, as well as providing different abilities to help out the other miners, and changing up the gunplay. The player can start an assignment that can be finished by completing missions. Once an assignment is complete, the player gets rewarded. There are multiple types of missions, all of them having a main objective, and a secondary objective. It is worth to do both, as it gives more EXP and pays more credits after completion. On top of that, there are occasional random events that can differ between collecting additional loot, or defeating mini-bosses. Always mine out Gold for more credits, and Nitra for ammo resupply, because ammo can run out pretty quickly. It is sometimes beneficial to mine out any unique or extra minerals, as they are needed for purchasing certain weapon and tool abilities, new weapons, and cosmetics. These abilities are locked behind level progression per each class. Enemies usually appear in waves throughout the mission, sometimes they're triggered by certain actions or progression, and there's plenty of different types of alien bugs to make the gameplay challenging and engaging. The more missions you complete, the more new weapons and cosmetics you can unlock. Additionally, you can complete challenges to get perk points to unlock passive and active perks for your characters. Once a class reaches level 25, they won't gain more EXP and levels, and the player has the option to apply to a Promotion Assignment, which when is completed, the class can then be promoted, resetting their level, but gaining a second active perk slot, and maintaining every weapon and tool abilities as well. There is a season pass as well, which is purely cosmetic, and all the DLCs for this game are also cosmetic only, meaning that you don't have to buy them to get the full experience with the game.

I tried to make this as short and understandable as possible, there's a lot more to talk about.
Rock and Stone brothers.