Improve my mobile game

Job ID: 33948867

Budget: $30 – $250 USD

I have a game build with my team, but there is something missing and I want to improve it, but I don't have a big budget for this.
Please check the game and let me know your ideas and how much it would cost.
The game is made in Unity.
Game is.on Google play store: Mecha Wars by Walko200.