What is needed for making mods are based on modern KeeperFX for example? Is C the only language I should use or there are some variations, what is the best way to make new maps and creatures, how does the process of making new models work and etc. Are there some guides and useful editors? For instance, I got an idea of mod with modified rooms functions and additional new creatures with specific characteristics aren't presented at usual game. They should include vulnerabilities and privilege against definite enemies, new abilities are also planned. The project is ambitious and may take much time and efforts. What do I need for this?