Too niche to be worth it.
InMomentum is a game which its name pretty much sums it all up. It's a first-person platformer designed to be played with a competitive speed-run focus. there's not really a "point" in doping anything you actually can do in-game except getting better and better, breaking your own records again and again. The single player is just about it, you choose one of the several stages, all very basic in style with a predominant theme, that's mostly not a theme, but actually a color. you choose which difficulty setting and between two different game modes that aren't too different in the end. Sphere hunt and time attack
Both games have the said spheres throughout the courses, but in sphere hunt you actually need to get them in order to finish the level, something not required in time attack. Both have in their core that the end time is what's important. As much as its leaderboards with times from players all around the world, the top scored ones are indeed quite good and the game, and watching them do their magic on Youtube is snappy as heck.
The actual controls are not hard to learn, though a little wierd at first. Most first person shooter have space bar for jumping while it has one of the mouse buttons. Wall slamming which is another important feature is also executed with the other mouse button. Thank goodness the controls are entirely customizable and should fit well to any player around. An essential feature that many high-end developers always forget about, especially for PC gamers.
The multiplayer is pretty much dead and has been dead for a while now. Of course the game isn't the most famous one around but the lobby system takes some of the blame for that. By default each vote for settings of a game session takes 60 seconds to end, there are 3 of them. You can go tyo the next if everyone is paying attention and swift but still not the best idea ever.
The multiplayer actually throws in some neat stuff in it. Actually those shiny orbs you get in single player can be obtained in multiplayer as well, but they give you special abilities like more acceleration, extreme jumps or slow-motion. Something like that in single player against CPU-controlled foes could work out. As far as the game goes as it is it's pretty much bland.
The actual momentum that give name to the game is executed quite well really. You have a velocimeter that tells you how fast you're going and as you accelerate you might reach insane speeds of 300 km/h or more. It takes a skilled player to maneuver the character at that speed. Wall slamming actually decreases you character a lot, so using it is probably a bad idea on more basic levels while it becomes necessary on more complex ones in higher difficulties. Like the impossible difficulty, the last one, kind of imposing isn't it?
You can also customize your character a little bit, it's not the best customization in the world, pretty basic stuff for a pretty basic character, but if you really enjoy the game you might want to do it. Of course it only works in multiplayer since the game is in first-person. Finding friends is not the easiest task in the world as it is, finding a friend who's into InMomentum is even harder.
In the state it is now this game is aimed at a niche market, speed runners that happen to find fun in doing the selected levels it presents them. Anyone else will have a hard time with the lack of game modes, objective and lack of overall refinement. Not a game I can easily recommend, unfortunately.