One of the purest videogame ideas is a room whose interior you can see but not access. Not yet, anyway. This is games' four four beat, its Alberti bass and its cadmium yellow. Sludge Life, which exploded into my life a few years back, a two-hour long game that has kept me happy for days on end, knows about the power of a room you can't get to. Not yet.
Why is it so good? Because that room festers. You try the handle, nothing. You can maybe see through a window but you can't fit. So you have to think, regroup, return to your core skills and see how you might use them differently. You have to try things that otherwise would never have occurred to you, and when you find new items and new skills, that room you can't get to yet is always there in your mind: hey, how about me? Is it my time yet? In short, you improvise, you test the boundaries of the rules, and you explore. And that, I hope, is videogames.
If you never played Sludge Life, you should play it now because it's free on Steam, and it's also everything I hope you will love: it's brisk, colourful, inventive, defeated, disgusting, exhilarating, curious in every sense. It's funny and burned out and gymnastic and cynical. It's a bottle-sized open-world with parkour and spraypainting spots and people to talk to and puzzles to solve. And it's free right now because there's a sequel on the way, freshly announced.