If you're an engineer, or wish you were, this is a great game. Build crazy rockets and watch them fail spectacularly. Accidentally learn more about orbital mechanics than you ever realized you were ignorant of. I've got 1000+ hrs in on this, finally playing on 'hard'. Definitely want a couple mods after you know what you're doing a bit, as they add things to the game that feel like they should have been in the core game (e.g. ScanSAT is awesome). This game is 7 years old, and I still play it. (fwiw, redshell was removed in v1.4.4)