Rebel Fortress Survival
You are left all alone in the fortress. The enemy decided to attack, so you need to hold on until help arrive. The idea here is to kill as many enemies that you can. No, there won't be any break since this is a continuous game. Your gun would get upgraded whenever you level up. There would be more enemies as you make some progress. The enemies would come non-stop and they would become even more powerful. Be sure to defend the fortress and not let any of the enemies get close to the base since they would start firing once they get close.