To complete the story mode of "Grand Theft Auto: San Andreas" and see the ending, players must complete the full sequence of story missions. There are a number of other objectives that must also be completed to get 100 percent completion.
The game does not always make clear which missions are mandatory to advance the story and which are side missions. In Los Santos, players must complete all available missions for Big Smoke, Ryder, Sweet, O.G. Loc and Crash as they become available. One mission for Cesar must also be completed, in which the player must win an illegal street race. The final mission in Los Santos is "The Green Saber," for Sweet.
Completing this series of missions unlocks the Countryside and traps CJ there for a while. Players must complete all available missions here for C.R.A.S.H., Catalina, The Truth and Cesar. The final mission in this sequence is "Are You Going To San Fierro?", for The Truth.
San Fierro is then unlocked. Mandatory missions there are for C.R.A.S.H., Kendl, Cesar, Jizzy B and Wu Zi Mu. The final mission in this sequence is "Yay Ka-Boom-Boom," for Wu Zi Mu. The desert area is then unlocked, and there is a short series of missions for Mike Toreno and The Truth before Las Venturas is unlocked.
In Las Venturas, players must complete all the missions for the Triads, the Mafia, Madd Dogg and C.R.A.S.H. After this sequence, the final set of story missions in Los Santos becomes available, and once these are completed, the ending will roll out.