There's Four In The Console Wars
Today Sega is merely a shadow (no pun intended) of what it was in the early '90s, but so many things could have went differently to make Sega stay near the top (mainly Sega Japan just leaves Sega America alone). So let's change these things and have Sega be one of the "Four In The Console Wars".
PODs
The PODs start with Sega America seeing the dying "Movie Game" trend in the early 90s, which makes Sega America realize they will need to start producing actual complete games for the CD addon, including namely Sonic CD and the original "Ghost Space", a horror game about outer space being filled with the ghosts of all those who have died (it will be a prominent title throughout this timeline).
The next part of these PODs is to do with the Saturn system, which in our timeline was a massive failure, mainly due to the nightmare game developers had trying to code for 2 CPUs and 2 GPUs and numerous other processors. Tom Kalinske, president of Sega America, did not want to launch the Saturn due to development problems. In this timeline Kalinske successfully tells off Sega Japan and begins work on an alternative to the Saturn (although using the shell/case of the Saturn). In late 1993 Kalinske successfully brokers a deal with Silicone Graphics to use their chipsets, and the whole of the console's hardware is modified accordingly, well retaining the shell/case from the Saturn along with the Saturn name. This change causes their to be 2 Sega Saturns: the "Japanese Saturn" and "American Saturn"; while both look the same their hardware is completely unrelated.
The final POD is Sega America begins working with Sony in early 1993, with Sony creating a CD addon that would be built into select "American Saturn" consoles along with games for the CD addon, all of this being done to help "perfect" the "American Saturn". The agreement between the 2 companies is that each company would get the money for what they individually made.
With this agreement being made the Sony "Playstation CD Player", as it is called in this timeline, looks exactly the same as in the Sony Playstation's CD tray in our timeline (taking up much of the console) but it's built into select "American Saturn" systems and is not a part of it's own console in this timeline. The version of the "American Saturn" with the "Playstation CD Player" was formally known as the "Saturn CD", and had a modified cartridge port put in the back of the console instead of the top; users would put cartridges in horizontally into the back of the console, and CDs would go into the large "Playstation CD Player" in the top of the console.
So, the timeline is set; now will come the pages on what occurs after these changes are made.