For me, Trackmania games have always been fun to play, and United Forever is no exception.
The game can be played offline or online, the latter being available once you create a trackmania account. In online mode you can race with other trackmania players or challenge them to beat your time on a certain track. In offline, you will basically try to complete the available tracks in the shortest possible time in order to earn medals;which in turn will unlock new tracks. You can customize the look of your car by choosing a predefined paintjob or by creating your own custom paintjob. There is also an editor in which you can create your own custom track. The game also has its own integrated benchmarking tool, you can tune the settings and then click on "bench" to see how much fps you're getting with your current configuration or you can save a replay and then perform a benchmark on that.
Now lets move on to the gameplay portion. Well, It is rather good, although at first it may seem that the handling is a bit too responsive for anyone's taste but it should not be much of a problem once you get the hang of it. Apart from the basic tracks there are "stunt", "platform" and "puzzle". In stunt tracks you have to achieve a certain amount of score by performing jumps in a limited time. In platform tracks it mosly consists of jumping from platform to platorm. In puzzle, you are basically given an unfinished track (in the editor) which you have to solve by connecting the start line to the finish line.
Most of the tracks are highly enjoyable and have such exilerating jumps that sometimes it makes you wonder "how did they come up with such an idea" or "how long did it take to design these". With all that said, there is one thing that i would've really liked to see, and that is "vehicle damage mechanics", it would've looked (and felt) so much better if it were to have that. But overall, i think it is a very good and well optimized game... THE END