We have experience in Unity 3D game design and development through state machines or C#, as needed.
We have imagined a limited scenario according to our bid, but there are certain things that should be set clear, since your description (and taking into account the use of the Word 'complex') then we believe that this might be a médium to large to enormous Project. So before we commit into a compromise, we need to evaluate your game design and negotiate our bid, or your game extent, whatever is best to our common interest.
What we believe that should be taken into account is the overall game design and level rules. Also, a first should be the visual guide. Game pieces should be decided and created. These may be created in Modo, Maya or Blender, and should be texturized accordingly to the visual effect agreed. Music and SFX are not mentioned, but we believe that should be settled too. The backend platform should be clarified, also.
We are very good at English as you can see, so we believe there should be no problem at all while interpreting and executing your game script.
You mention a couple of comercial games. We need to agree on this point, since you should have into account that you are asking for bids that represent less tan 10% of those games actual Budget.
So, please, allow us to talk and define with you a succesful game in a win-win agreement within your limited resources. We don't want just your money, but a long term relationship.