Press 'ctrl+R' in the game to switch modes.

I tried it but nothing happens, I set machine=cga and it start on COMPOSITE mode and then i tried to press CTRL+R on in the game but nothing happens...

If you are using the version of the game that game designer Al Lowe has made available for free on his website, then the answer is that you cannot enable RGB mode. (The version on Al Lowe's website is the Amiga version's data files with a PC interpreter executable.)

Only the actual PC version, which is a self-booting game, supports CGA RGB mode. You can find out which version you have by pressing Alt+D. The actual PC version says "Version 1.0Q". If it instead says "Version 1.0C", you have the Amiga version with a PC interpreter executable, and if it says "Version 1.0A", you have the Atari ST version with a PC interpreter executable. (A later file-based actual PC version saying "Version 1.50" also exists, but it extremely rare, and only supports CGA RGB mode when run with the -r command line option.)

WOW THANK YOU SO MUCH 😀
This is amazing information, where did you learn all this info, I couldnt find it (I did look for some info before posting this post)