This preview originally appeared in issue 248 of PC Gamer UK.
In a platform game, the screen is usually divided between solid land and empty space. The empty space is the fun bit – you can jump around in it, fight enemies, solve puzzles. Usually nothing very interesting happens inside the solid ground beneath your feet.
In Ibb and Obb, the solid ground becomes the empty space for another platformer, one that takes place upside-down. Portals in the 'ground' let you jump into that inverted world, and walk on the underside of the same floor you were walking on top of just a second ago. There are no blocks of solid ground anywhere, just a thin barrier between these two worlds.
It's brilliant. It's a co-op game, but both you and your partner are free to move between worlds – the challenge is to figure out where each of you should go to help the other through obstacles. Some of the portals work for both of you, but others are colour-coded to only let one of you travel through. Often, that gives one of you freedom to roam in both dimensions, while the other is stuck in one until you help them.
The puzzles start pleasingly simple, and slowly scale up in complexity until they're as brain-bending as anything in Portal 2. In fact, Portal 2 is a good comparison: almost every puzzle in Ibb and Obb requires both of you to help each other, and the cerebral puzzling is mixed with some very satisfying momentum mechanics.
My favourite things in the game are the bounce pads. They don't bounce you. All they do is transfer the momentum of any impact to the other side – and hence the other world.
So if one of you stands on top of a pad, the other can go into the upside-down world and jump onto the underside of it to send you flying. It's a great feeling, and it serves as the foundation for some truly inspired puzzles.
Playing with Chris, I found a pad that seemed completely useless to me: it was on a raised platform, so I couldn't get much height to jump on it, nor did I really need to be propelled into the air at that point by Chris jumping on the other side. But a raised platform in this world is a pit in the other – one too big for Chris, in the upside down world, to cross.
So I stood on the pad, Chris jumped onto its underside and sent me flying into the air. So far, no use. But when I landed, the impact sent Chris flying back up out of the chasm he was stuck in, letting him make it to the far side. I had essentially been a storage vessel for his momentum, borrowing it from him when he landed, then giving it back when I came down.
That's a beautiful trick of physics. Generally, too, Ibb and Obb is beautiful. There's a gorgeous elegance to its simple art style, and a perfect economy to the way it uses space, both above and below ground. It's engrossing, clever and fun.