1. I suggest you change the name, as "Super Ogro Kart" sounds a lot like
Super Tux Kart or other kart racing games.
2. You have maybe 3 pictures of the game. that's not much of a preview. A video would still be nice. The more action people can see, the more likely they'll try out the demo.
3. Looking at the demo, it's not even technically a demo; it's a map with a TON of unnecessary .bak files. Remove them. Also get rid of the thumbs.db files.
4. The way you're trying to market this is as a separate game or a mod when it's not quite that way. I realize the demo is a single map and that there will be more, but to make this your own game, you're going to have to change some things, especially since the vehicle simulator in Sandbox is not in development and is unfinished.