[hfsktr]

From all the comments here I was expecting it wouldn't work at all without signing in somehow. Luckily that wasn't true and the site didn't seem slow at all so I got to actually try it.

I did like it but really wish there was an explanation at the end with the solution (or a solution). Since I don't know what is wrong I don't even know what to search for.

I am not sure if you have categories for the types of problems but dividing them into syntax/logic/easy/difficult/etc and showing your score on those or even compared to others (this might be what signing in does for you but I didn't do that).

I am sure I sound negative but I was impressed. Especially as it's still in progress.