I've been playing Space Engineers since it released on Steam. Before symmetry mode was a thing, before survival mode, before thruster damage or multiplayer or many common mechanics were implemented.
I've got nearly 430 hours into it now, and I'll definitely rack up a lot more. Here's why.
Do you want to build a racetrack in space and dash around in gravity-tethered go-carts? You can do that. Demolition derby? Sure, that's feasible. Starfighter dogfights? Yup, you bet'cha. Capital ship slugfests? Seen 'em, they're pretty. Just build without restrictions, build whatever you can imagine? Ayup. Survival mode? Oh, oh hell yeah.
Sometimes sketchy, but generally reliable as of the last few patches, Space Engineers multiplayer is genuinely fun. Not in the shoot 'em up bang bang pew pew sort of way, more of the mutual cooperation so you don't all suffocate and die horribly in space sort of way. It's a huge change of pace, and the recent updates have made it feasible to do more than merely survive. You can explore, you can wander the 'verse and see all the beauty and horror it has to offer.
Dem physics doe. Needs a little fine-tuning in places but it works out brilliantly otherwise, and allow for artificial gravity and zero-gravity to happily coexist. Crashes are spectacular, damage from kinetic torpedoes is impressive, and for the non-combat oriented, it's just plain fun to fiddle with the physics in this game. From making orbiting satellites to devising new and innovative ways to send things flying at ludicrous speeds.
KSH is awesome. They push out updates every Thursday, barring major holidays or a sudden and inexplicable bear assault on their offices. They work hard to keep the game up to snuff and it shows with just how far its come in relatively little time.
-Steam Workshop Integration
Seriously awesome. Want a mod? Grab it. Want to play with someone's ship? Snag the blueprint. Want a new skybox? Done. New world? Easy peasy. Workshop is an amazing tool and it allows you to very easily - and very rapidly - add new spins on the base game.
-KSH is awesome
So good they deserve their own bullet point. These guys work hard, are creative, are pretty honest about where they're at and what's going on, and push out updates and fixes like clockwork. They're enthusiastic about their product, they're in touch with their playerbase, they listen to their playerbase, and they're willing to learn from their mistakes so that they can overcome future hurdles. They're working hard and the game is only getting better with each passing week.
If you're on the fence about this game, don't be. It's a good, solid title. It has its bugs, yes, it has its glitches and its problems, but they've spent several weeks weeding out the bulk of the problems and it plays pretty smoothly now. There's modding support, multiplayer, survival mode, creative mode, and they're rolling out exploration-oriented content - plus patches every Thursday. Not much beats that.
If you like building games, buy it. If you like mining games, buy it. If you like exploring, buy it. Some folks say it's minecraft in space, and in a sense it is. It's virtual legos for sci-fi gamers and hopeful shipbuilders, and it's just flat-out fantastic for it. Strongly, strongly recommended.