Nations has been created on a commission from the Electronic Sports World Cup, hence the tag, and serves as a training platform for the actual event, which takes place in Paris in the summer.
You get a Race mode - much the same as that of Trackmania or TM Sunrise - as well as the usual track editor, so you can plough through a range of simple-to-insane tracks against the clock and design your own to race with online. Online racing's supported in full.
As you'll know if you read last week's hands-on preview, the ESWC is putting up $40,000 in prize money for the TM Nations tournament, so it's worth having a go.
Check the official ESWC site for more details, and whether you fancy it or not, download TM Nations ESWC and give it a go. It'll probably eat your whole evening.