I am making an iOS game for a project at school. It is going to be a tiny bit like Fruit Ninja, as in it will have different things on the screen, and when you hit them, they die, and you get points. The trouble is that unlike Fruit Ninja, my game will have different types of sprites, all doing different things (moving different places, doing different things, etc). The one thing that is bad about having all of these sprites that do different things is that it is hard for them to look neat on the screen all together. I was planning on having a couple of different gamemodes:

Time Trial
You have 120 seconds to kill as many sprites as possible.

Survival
You have three lives, every time you try to hit a sprite and miss, you lose a life.

????
Whatever I think of.

I am a rookie to game design in general, and I don't know the best way to make my game look good, and play well. I could have all of these sprites on the screen at the same time, or I could have them come in waves, for example 10 of sprite_a come on, and once they are killed, 10 of sprite_b come on, etc...

Please give me your opinion about which one I should code. If you have any other suggestions for either a third gamemode, or a completely different way to make the levels, feel free to tell me.