I've been looking for new scenarios to play. However, most on this site seems to be completed parks. I've found a few which aren't, but not many. And it's hard to know which ones a actually good and not when almost all parks are completed when sorted under downloads.

Anyone care to save me some time and suggest some good medium - very hard scenarios?

Thanks!

Look into Neton for RCT3. It is a huge pack of CS and custom scenarios.

http://neton.rct-net.de/