Segato Sanshiro said:
Okay, so let's assume they go with the combined sales and thus FFX/FFX-2 The Two-Headed Monster becomes the inspiration for the gameplay of FFXIII.
The first obvious analogy to draw is X/X-2 and XIII/Versus XIII sharing the same "double-dip" strategy. If the two games share the same world and run on the same engine it makes sense to have some bleedover in asset use between the two skus.
Its a smart way to mitigate the obscene cost of asset production, and allows you to create a timely follow-up.
Final Fantasy games have a very schematic design. By this I mean elements are nested inside elements, but remain distinctly separate from one another. The classical example of this is the segregation of field and battle modes. The levelling process (RPG element) is entirely the province of the battle game. be it level 1 or 100 the overworld remains fixed and constant.
By the same token, progress through the overworld is moderated by the story. Can you see where I'm going with this?
In the first iteration (FFX) the story unfolds in a fixed linear path. This is because the world is new and unfamiliar to the player at this point and it makes sense to introduce this incrementally. The only linkage between this and the RPG base is the spawn lists for the zones being revealed to get tougher mobs the further the player gets.
In the second iteration (FFX-2) the world has lost its mystery so going a non-linear route makes sense. The overworld only needs minor alterations for continuity with the first installment, and you can completely hot-swap the battle and RPG system because it has no mechanical connection.
The key thing is that although the battle system is different, the behaviours of the mobs are completely unchanged. Outside of story bosses, you have all the meshes, animations, vfx, ready to go. All you really need do is remodel the PC animations, and change the way the battle flows and bobs your uncle... boom! new game same quality as its predecessor in 1 year.
In FFXII you already have a lot of freedom to explore in a quasi MMORPG style. Problem with that is how do you sequelize it without making it look like overgrown DLC or a "director's cut"?
Its easy to take a linear structure into a non-linear structure, because the spatial relationship between the zones is enshrined in the narrative and you have novelty on your side. Going the other way is not nearly so easy, especially if you want to forgo the cost of building a ton of new environments to link stuff up in new ways.
Then you have the problem of the battle-system being much more integrated into the field system in FFXII. You cant just swap out the old battle system without adding a lot of cost overheads if you want to do it radically differently.
The point is that the way SE have gone by making FFXIII linear makes a lot of sense, especially as they are planning a follow up in a short timeframe with Versus.