For all games I have rights. But Polish law is more complicate that other ones. I can't putt it free with source code or made freeware, because many games was written by other peoples. So, I have rights to sell it or/and put as abandonware, but for source code and for changing something in code are only authors, wchich made code, msx, gfx etc. Yes, it is complicate for peoples outside Poland, but Polish law is as is.
So, please don't ask me for rights for changing any byte of code. It's impossible in my country law. Peoples writed games for me wasn't employers of my firm, they comes from outside. And - in Polish law - it can put me only finansial rights for they programs. But thay - in lawer case - can't change any byte of code without my permission. But I can't put them my permission, because any changes in code change version, so I must pay them for it, if I want do it. If they want change it without my permission - they can pay me for it, because they sell me financial rights for it. So - thay can't do it. And circle was rounded.
So, if you can't be happy to use it free - simple don't play for it. Polish law is terrible, as I said.