I am interested in having a character who levels up, but skill trees have been pretty rehashed. What if the game catalogued and analyzed your general play style for that level and gave you two or three options to improve your methods? Every so often, special skills would appear as an option too. [u]For example:[/u] You're playing as a Titan and the game notices you rushing into the heat of battle. You're given the option to increase movement and reload speed, or receive a small bonus to DPS when you level up. At a later tier, you're playing as a Titan and the game recognizes that you've been playing a tanking role. When your character levels up, you're given the option to significantly improve health/shield regeneration or a special skill that draws enemy fire and makes you invulnerable for ten seconds, but your character becomes immobile and unable to fire for the duration of the skill. Those were just some rough examples, and I realize this would be difficult to implement, but it would be cool to have characters who leveled up to meet our play styles.

What if all the skills were available eventually but it took a ridiculous amount of time to get them all so that you would still see specialization.

I think the idea of skill tree is kinda a bad idea, because you can make your character unice by modding your weapon, camo, armor. It is three types of character, and they should have differece abilities and that should make the game more that unice. and then the characters/players must trust the other players to do their "role". The titan can probably rush in and the warlock can cover the titan with a big ass sniper, and the hunter can flank and take the enemies from behind. this should make the game very tactical and fun.

I'm really interested to see what Bungie does. I thought Skyrim had a really innovative (albeit executed so-so) "be who you want by doing it" model, but the fact that they've added classes into the game makes me think that model has been eliminated in favor of a skill tree type system. I think the tried-and-true skill tree model can be done really well, but you really have to contemplate balance. The only thing that makes skill tree elements vanilla is when some skills have little or no use, and only a few "builds" are utilized by players. That wouldn't be so great. Also, I think the fallout Perk system is a really awesome thing to add into games. Not so much the system from Fallout 3 and New Vegas, where perks added significant combat bonuses to your character, but the perk system of Fallout 1 and 2, which were more screwball-style things that made your character truly unique, and ensured that interactions and situations always played out in a unique way.