Well Demon's Souls and Dark Souls, while not being true sequels, are spiritual predecessors/successors of each other with a unique naming scheme. I like their naming system, and would certainly like to see others do the same.
The Elder Scrolls does it alright. No one refers to them using number, and very rarely are they even referred to using "The Elder Scrolls." The vast majority of references just use the location name (barring Arena and Oblivion). So while the full name is, for example, The Elder Scrolls V: Skyrim, it is commonly referred to using just Skyrim, taking the number issue out of it.
Edit: For larger series, like Halo and Star Wars, it is justified in having the universe name in the title, but it still should have something besides just a number for main releases. Everyone knows what you mean when you say Knights of the Old Republic, for example, and Star Wars: Knights of the Old Republic works well.
Halo: Reach works well. Halo 3: ODST, however, sounds like an expansion of Halo 3 and not a full-blown game.
The Elder Scrolls does it alright. No one refers to them using number, and very rarely are they even referred to using "The Elder Scrolls." The vast majority of references just use the location name (barring Arena and Oblivion). So while the full name is, for example, The Elder Scrolls V: Skyrim, it is commonly referred to using just Skyrim, taking the number issue out of it.
Edit: For larger series, like Halo and Star Wars, it is justified in having the universe name in the title, but it still should have something besides just a number for main releases. Everyone knows what you mean when you say Knights of the Old Republic, for example, and Star Wars: Knights of the Old Republic works well.
Halo: Reach works well. Halo 3: ODST, however, sounds like an expansion of Halo 3 and not a full-blown game.