It's a choose-your-own-adventure book wrapped in nice html engine. Gameplay is not that easy, mainly related to risk management under the time pressure, which takes time to master. Overall, it would take few days at least to get to the true ending. And you gonna enjoy all of those days, if you like reading of course. Descriptions and narration are top notch and really do immerse the reader into vast mostly lifeless expanse of space.  Choose any 'grounded' space epic of last decade, like Interstellar - this game beats it in quality with ease.