Lolzipop said:
Think about it. Rails can ADD to gameplay. Rails don't force you anywhere; you have the option of whether or not to jump on them, and you can jump off at any time. In fact, you might be able to hide some hidden items or stuff like that in SRB2 by having a rail going down to a platform down below, and there's a platform in the wall on the way down that you can't reach unless you jump off the rail at the perfect time. Rails might make the game linear, but in the end it's all about how you use them.
Rails do not accomplish anything a normal platform cannot accomplish. For instance, if you wanted to do something similar in SRB2, you could make a water current push the player, and they could reach a powerup if they jumped out at the correct time. Part of what makes SRB2 good is that if the player wants to attempt something different from what the designers intend, the game is not going to stop them. Rails, especially rails over bottomless pits (Stupid Final Rush), remove that feature from the game. Essentially, the player is forced down a specific line where he has to follow a set path.
Even if the rails are optional, they're surely going to be part of the optimal line through the stage, which means time attack or race will be inherently boring, as it removes most all of the movement commands from the game. I mean, watch someone good play a stage in SA2. Then watch someone else good play SA2. In all likelihood, the run will look nearly the same, because of all the forced sections, where the player has to grind a rail or otherwise cannot change directions, such as those stupid enemy homing attack pathways. Now watch someone good play SRB2. Then watch someone else good play SRB2. While a lot of areas will look similar, they will most certainly deviate in their methods and paths a bit as they try and take a line that works the best for them. This is what rails remove from the game, and honestly, I refuse to even consider to add a feature that encourages bad level design. Instead of using rails, might I suggest current or wind to force the player to move forward?
Lolzipop said:
EDIT: And "forward-only"? Almost correct; you can go backwards on them too.
Well, in most of the modern Sonic games you can only go forward on them, because the camera will glitch up if you try to go backwards anywhere in any section of the stage.
However, 2 directions, while better than 1, is still MUCH worse than the full range of movement you get while walking. Rails, by design, are a restrictive game mechanic that removes player freedom. This is not a problem in Sonic Adventure 2, as there wasn't any player freedom to begin with, but in SRB2, it's just a bad idea, through and through.