Check out Freespace Open http://wiki.hard-light.net/index.php/Source_Code_Project_ind.... The engine for Freespace and Freespace 2 was open sourced and has been under continuous development for ~20 years. They've remade the rendering engine about 3 times to keep up with AAA titles. All of the ships have been re-modeled and textured to look great. You can play the original campaigns with the updated engine and graphics but there are also about a dozen fully voice-acted campaigns made by fans, some of which like Blue Planet and Silent Threat Reborn are utterly amazing. For $4 on GoG, it's hard to beat the shear number of hours of (really impressive) play time you'll get with the community improvements.