1. Make A Reasonable Amount Of Enemy's
2. Make It Not Too Hard And Not Too Easy
3. Put Allot Of Detail And Art Into Your Game
4. Make It Long As You Can (If Possible)
5. Put Cookies,Hearts,Checkpoints,Medipacs And Much More. So That If You Have allot Of Enemy's You Could Put Hearts,Checkpoints .ect.)(So That The Player Doesn't Die Easily.
6. Put Music On Your Game For Entertainment)
7. Make Sure The Game Is Possible (Well We All Say Everything Possible But There Are Some Games On Sploder Which Are Impossible!

I Hope This Helped You Out I Will Be Making More Topics Soon!