If I were you I would take a look at killing floor and use it as a playable reference. It looks like you are going for a horde mode gameplay and if that is the case you can do all kinds of interesting enemy types that attack in different ways. Lots of weapons! Weapon choice is a must in games like this but they all need a purpose or a feel to them so players will want to use them. Another thing you can do is see how other horde modes are played and try to build a new system or mechanic so it isn’t just killing and staying alive. No matter what lighting is always important but it looks as if you are going for a dark possibly scary setting and if that is the case do a lot of research on lighting and dark environments. It can really make or break how the player feels when playing.
Anyways, just a few thoughts. Use it how you want. good luck!