So I am working on this top down shooter game which at first was supposed to be an RPG, but I now decided to make it a simpler shooter. And the problem is that it's not fun. All you do is run around shooting zombies, leveling up and collecting new weapons. I need to make it more challenging, but I have no ideas. I also need to make so that the player would feel rewarded if he plays well, but I don't know how to do it well. 

If you guys have any ideas for game objectives, or fun game mechanics that would fit my game, please share it with me.

You can see the footage of my game here:

Doesn't really look like top down. 

I am not a fan of the zombie genre, but why not make something complete different, or did you browse the projects people have posted on this very site to get some inspirations?

You could improve enemy AI so they can form flocks and have the ability to surround the player and collectibles, and they can block a narrow path to proceed to new areas (currently the player can go anywhere without concentrated resistance against him).

So for the player it becomes much more satisfactory to collect, power up and proceed.

Also this gives the player a better reason to attack enemies at all. (Most games just throw the player into something and he has to kill anything that moves. Without a reason that's not motivating. A bit of story can help here too, e.g. showing how zombies ate his girlfriend.)

You should also show the gun he has, better guns become bigger, and black bullets would be better visible.

Hi, my two cents:

- all you basically can do right now is run around and shoot, and shooting doesn't look fun. Instead of just a ball(?) show a gun on the player, show projectiles and let shooting have more impact. It needs to go !!!BOOOM!!!, things should splash around and be destroyed, a visible and audible reaction to the bullets and explosions. And show the aftermath, let bodies and gore lie around. Check this:

- it doesn't look as if it's hard to evade the enemies. Perhaps add more types of enemies, a few faster ones, a few that explode close to the player, a few that can shoot, the usual stuff. Also let the player move into confined spaces, so that it's actually harder to avoid enemies.

Good luck!

Guys, big thanks for the replies, you helped me out alot, I added blood particles, shaky screen, smooth camera movement, bigger and faster bullets, louder shooting sounds and now it feels a lot more satisfying to kill stuff

Add more need of food or ammo or something so that the player is pressed for finding supplies. They they need to split their attention and surviving becomes more meaningful.

Maybe have periods of calm where you can apply bandage, eat some food before the shit hits the fan again. More variety: calm sections and really hectic ones. Now everything seem like the same thing.