Single player, various difficulties, and more than a statement mario kart in hard mode, the multiplayer friend (s) up to 5!
And online multiplayer also up to 10 or 12, I forget which 5 local can participate.
different modes: race / battles
changes in current race course.
Only downside maneuverability in flight mode (among kart / boat / plane), not always obvious ... hence the 4 stars.
(NB if you're struggling to join online games, it certainly comes from your ISP, I changed because of it, and since it is Nikel!)
I recommend this game!