It might just be me, but I feel much happier when I complete something frustratingly hard and get a great reward for it.
Hence why I didn't feel anything special when I beat time attack.
That's fine, but as designers, that model simply isn't a good idea. Let's take two examples:
Pokemon Diamond/Pearl have multiple main goals in the game. The first goal is to complete the game and beat the Elite Four and the Champion. The second goal is to complete the regional Pokedex. The third goal is to complete the national Pokedex. Each of these goals is successively more difficult. The designers expect most every player to be able to beat the Champion, and therefore a significant amount of material is unlocked when you do so. When you complete the regional dex, another significant amount of material is unlocked, because the designers generally expect most players will be able to do that. When you complete the national dex, however, the game doesn't unlock a whole lot. This is because the designers assume that the vast majority of players will never actually achieve a full national dex. Instead of providing significant new content, the game provides easter eggs to those that actually stick it through ones of the hardest tasks in the game.
What this means is that players don't feel compelled to complete the national dex unless they actually ENJOY the process of catching every Pokemon in the game. Those players that actually do succeed (myself included), are far more happy with the satisfaction of actually completing the task than any in-game reward the game actually provides for it, because they took it upon themselves to try for such an unrealistically hard goal and succeeded.
As a counter-example, let's take my personal whipping boy of unlockable design: Sonic Adventure 2.
Like Pokemon, SA2 provides multiple goals for unlockable rewards, culminating in the ultimate challenge of collecting all 180 emblems. Unlike Pokemon, though, SA2 provides a significant reward for the unrealistically hard goal: Green Hill Zone in 3D. This is an incredibly cool reward for many people, and therefore, almost everyone tried for it. The problem is that the process of unlocking it is insanely tedious. It requires both getting As on every stage in the game (except Cannon's Core lulz) for all five missions, but also collecting all 10 emblems for grinding in the chao minigame. Even worse, with such a variety of gameplay, it's pretty likely that someone who tries for this goal is going to end up doing something they don't actually enjoy because they're trying for the carrot on the stick at the end. I can tell you personally that if I had known how tedious grinding my Chao's stats was going to be, there is no fucking way I would have EVER seriously tried and instead I would have simply used a cheating device to get there.
This style of ultimate unlockable design simply encourages players to do things that they don't actually enjoy in order for the reward at the end. I hated the Chao minigame, but I spent hours of my life playing it purely to play Green Hill, because they put the cool unlockable behind an unrealistically hard goal.
The point here is that unlockables shouldn't require the player to do absolutely everything in the game to see everything significant there is to see. Forcing players to do that will cause them to do things they don't like to do. Imagine how much better of a game SA2 would have been if that gigantic emblem grind was simply a cool goal for those that like 100% completion, rewarding you with Green Hill at perhaps 80% of the emblems instead. Imagine how much WORSE Pokemon 4th gen would be if there was a significant amount of unlockable content if you completed the National Dex that most everyone will never actually get to play, and encouraged players to do something they might hate.
SRB2's unlockables in 2.X are aiming to be more like Pokemon in this regard. We have plenty of unlockables, but most of them are relatively easy to unlock. We genuinely expect most players who actually put forth real time playing the game to beat the game with all emeralds, for example. What we DON'T expect most players to do is complete many of the significant challenges in the game, such as Ultimate mode or getting the Time Attack emblem. This is why the rewards for being ultimate and getting all the emblems are more token rewards than anything else. I don't want to encourage players who may hate Time Attack to feel compelled to complete it simply to unlock some cool stage. I don't want to encourage players who may hate scavenger hunts to feel compelled to find all the hidden emblems because they'll miss out on something really cool if they don't. While you may be disappointed that we don't give you some epic unlockable along the lines of Green Hill for completing ultimate, I think that's FAR better than encouraging tons of players that may hate ultimate mode to play it just because they feel like they'd miss out on something important if they don't.
Hence, you should not expect any major unlockables for 100% completion or other insanely hard challenges in the future of SRB2. The reward for beating ultimate mode is the ability to say that you've completed ultimate mode on the forums. We also provide a little easter egg for those that went through the trouble, but that's just a token on top of the satisfaction of actually completing one of the hardest challenges in the game.
