This game isn't "fun" in the sense of having a wacky goofy funny time with wacky goofy funny enemies and mechanics like backrooms or Nuclear Nightmare. Its more "fun" in the sense of immersing yourself in a tactical, puzzle solving environment, This game is more serious and linear. More punishing and tough. An experience through a tactical campaign that tests your tactical abilities, your communication with your squad, your aiming, quick thinking, and reflexes.

Yes it is absolutely fun but for different reasons. If you're looking for goofy wacky funny, this isn't it.

It's fun but still fairly rough around the edges. I recommend waiting for another major update or 2 before getting it. The devs have passion but progress has been a bit slow.
https://store.steampowered.com/app/427410/Abiotic_Factor/
Abiotic Factor is going in to 1.0 in less than 2 weeks. This game definitely has that special something you're looking for. If you get it while it's still in early access you get free access to the supporter edition content that will be coming. Also there will be cross play with the consoles in 1.0 if that's important to you.

Yes, but no if you're not good at tactical shooters. Its very punishing if you die

it's the ideal game for co-op