You've done it the wrong way, Ulf. Publishers don't want to pay for something that is already developed. People want what they don't have. A [censored]-hot demo that will will take until just before next Christmas to complete is a far better sell. They'll want to input their own ideas too.

Be careful with open source. Avoid GPL. Publishers want what they can buy lock, stock and barrell. You'll probably see a clause in the contract they present to you about that. They'll want the copyright. Make sure everyone who does work for you has a contract that stipulates "work for hire" as well. Otherwise you might find that you don't have anything to sell. Anything you absolutely don't want to give them, list as royalty free, licenced material (you can licence material to your own company). However, they will expect some bang for their buck. Obviously, they are the ones taking the biggest risk.

Four months is very short for a video game you made yourself. Commercial titles are usually measured in man-years. If you made it for yourself, because you liked doing it, then that's fine. If you want to make it for someone else so you can make some money, then you need to balance what you want to do with what your source of funding has a demand for. Unless you are a proven, multi-million selling superstar, then you can do anything you like and make megabucks.