The way I got the Raskulls trial was to Click on the Raskulls Blueprint option, under the "build" menu, in World of Keflings. It asked if I wanted a Trial, to DL the full game, or back out, thus I selected the free trial.
I have to say, Raskulls is insanely charming, and I really wish I had it around back in the SNES days; the music is peppy, the way you select power ups when racing feels JUST like Mario Kart (even the sound effects are similiar), and the Megaquest mode is nicely fleshed out, with loveable little cinematics. The theme music + node gameplay of the quest really feels like a mini rpg, which I wouldn't mind seeing with these guys.
The Mr. Driller meets Racing gameplay seems pretty nice; it's like a "Dashin' Desperados" + "Driller" hybrid. The stages open with a variety of startpoints, leading to various chokepoints, which give you chances to rumble VS your competition, either directly (flame dashing through them, shocking them in the butt), or indirectly (solving quick puzzles in your path, and hiding in the safe areas as the world comes crashing in on them). It really helps keep the pace going well.
The party-game aspect, the atmosphere, and solid graphic work (I really like the style, personally) really make this feel like the perfect compliment to, say, a night of Bomberman, or something of the sort. Heck, I'd say I enjoy the presentation more than the recent Bomberman games, as it just seems more polished, whimsical, and developed. Kinda reminds me of an HD version or, say, "Megaman Powered Up".
I should note that characters unlocked in the Megaquest are opened up in multiplayer, so you do appear to have to play the Single player content to get all the characters for multiplayer. As I've just played the trial, I don't know if you can unlock things through online play (Or if the trial has online play, as I didn't even try the option.)
Leaderboard integration seems nice too (the boards pop up on the map, when you move over a stage in the quest), and there's some variety in the mode (From default races, to speeding through while maintaining frenzy mode, to making it through the stage with a limited number of block-destroying zaps), so it really seems to take it's structure as far as it can.
I'd say it's worth a look, and looks to be a solid buy at 800 pts. Even with all these sales in the next few days, I'm rather tempted to get it...