A JCSer's decision to stop working on something is always a good decision, even if people who look forward to see it disagree. You can't and shouldn't force yourself to work on something you don't want to work on. If you're really sure you won't work on something anymore, releasing the unfinished product might be a good idea though. You might inspire someone with it, or at least let people have fun playing some new, even if unfinished, SP levels.