Project Gemini for REENTRY is one of the spacecrafts available for flight and is a study level implementation modelled after the real spacecraft.
The goal of the spacecraft is to mimic the real spacecraft flown by real astronauts. The capsule is modelled after the Project Gemini Familiarization Manual SEDR 200 – RENDEZVOUS and DOCKING CONFIGURATIONS (Vol. 2).
The implementation is focused on the Capsule 8+ configuration, containing Fuel Cells as the main power source, as well as 4 main batteries and 3 squib batteries. The differences between the configurations with Fuel Cells are minor, so with the configuration implemented here, all the Gemini missions could be flown.
All training needed to fly the capsule is available in the REENTRY Gemini Flight manual and through the in-game Academy. If you want to study the spacecraft down to the lowest details, I highly recommended to read the manual by NASA. The manual is divided into two different manuals. The reason for this was that Chapter 8 (Guidance and Navigation) was confidential.
The Project Gemini Fligh Manual for Reentry is a custom flight manual I wrote for the purpose of this game. It's still a draft but it describes how you operate the Gemini capsule, as well as its systems.
This is the official manual by NASA, and is used as the basis when implementing the logic of the Reentry Gemini implementation. I highly recommend reading this to get familiar with all the systems at a deeper level, but this is not required to play the simulator. This is the main manual, with exception of chapter 8 covered in Vol 2 - section 2 (below).
This is the 2nd section of the Gemini manuals, and covers the guidance systems of the capsule.