TrackMania Nations Forever
There is such a thing as a free launch ramp.
It's designed for e-sports, but also for just having a stupidly excellent time mucking around with. And while it doesn't contain Puzzle or Platform, it does nod toward the latter with its "Obstacle" courses, which require some inventive leaping and bouncing. But more than anything, it's 65 tracks for free! Free! And you can play online against the world, both in the solo mode, or in the madcap, sometimes unintelligible multiplayer mode.
TrackMania cars can't touch each other. Everyone's a ghost to everyone else. So in multiplayer you're all on the same track at the same time, racing to see who can get the best times, but starting whenever you like. It's bedlam. It's also ranked on the international ladders.
Nations Forever also comes with its own track editor, so it doesn't end with the 65. Downloadable player-created content means the game will expand to infinity. You can customise your cars with the painting facilities. You can edit videos of your own driving. Then there's Party Play for LAN and a gang of people sat around one computer, and the Explorer, which works like a cross between a mini-internet and a social networking site, from which you can download tracks, replays, movies, etc, created by other players.
If you're picking up Forever to expand your copy of United, you won't only get the new "Nations" category in your sidebar with the new levels, but you'll also find there's extra materials appearing in the track editor, and a graphical overhaul of the original race categories, Desert, Snow and Rally, to bring them up to speed with the more recent courses.
There's some (more) confusion over the pricing of picking up United Forever new. The US price on Steam went up from USD 30 to USD 40 when the free add-on was added (it's stayed at USD 40 for Europe). Which doesn't seem so free, but of course it's within Nadeo/Ascaron's remit to charge whatever they wish for their game. It does seem a bit much to increase the price of a year-old game, and the new retail version will of course cost more than finding a year-old copy of United and then adding the download. Um, we recommend you do that quickly before the shops switch them all over. You'll miss out on the 3D glasses, but, well, yes.
In the cold light of day I can tell you, emphatically, that I love TrackMania. In the cold light of day I was able to get the Gold and move on. If United got anything wrong, it's that it was too hard. As the lead dev, Florent Castelnerac, said in the comments of the United review, "I even [can't] get the gold medal on the last one: PlatformE, but I wanted to give lasting appeal to the expert out there." Forever's new tracks absolutely nail the difficulty. Oh, and by the way, the minimum specs are a 1.6GHz CPU, 256MB RAM and a 16MB video card.
I'm not sure what a gift horse is, but I'm told one shouldn't look at its mouth. I don't understand how this is relevant. Meanwhile, get a copy of Nations Forever, or for goodness sake upgrade your United. This is a ludicrous amount of excellent fun to get for free, and in that price bracket, it automatically gains an extra point on the Out-Of-Ten-o-Meter.