look at MUDs. some of those are fully programmable. i am most familiar with LPmuds, which are written in LPC, which is a complete programming language. (Pike a general purpose programming language is derived from LPC. and there are also a few small MUD engines written in Pike)
though for a standalone game a full MUD may a bit much since they are designed for large words with hundreds or thousands of players. but take a look at the available game engines and see which ones come with decent documentation for you to get started easily.
though for a standalone game a full MUD may a bit much since they are designed for large words with hundreds or thousands of players. but take a look at the available game engines and see which ones come with decent documentation for you to get started easily.