Couple of Ideas for D3

[ComatoseSoul]

More Hidden Areas:
Would love to see more secret areas like the cow level, ubers, etc...

Hidden Skills
Some kind of synergy system that unlocks new skills. Using the current D2 skill system as an example: If someone were to max both Skeleton Mastery and Golem Mastery it would unlock a new skill: Summon Balrog. Etc... Basically adding on to synergies where not only can you boost skills, but unlock new ones through different skill combinations.

Dungeon/Level Editor
(This would depend on what Blizzard ends up deciding about level randomization.)
I think it would be cool if Blizzard could figure out a way to include a level editor that allowed the creation and introduction of new areas to Battle net without breaking the game's ambience. You would be able to set mlvls, resists, monster abilities, in addition to level design, monster placement, chest placement, trap placement, boss placement, etc....

This could even be a challenge type system where you did not earn experience, but Battle.net would keep track of what custom dungeons you had completed, how quickly, how many deaths, etc... Maybe it could be completely separate from the normal multi-player game. So instead of just a level ladder, you also had a ladder based on who had completed the hardest custom dungeons.

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Just a couple of random ideas - bored at work, and looking forward to D3.

[Nimbostratus]

For hidden areas, I'd like to see some extras that AREN'T endgame. Finding some secret passages in the mausoleum after defeating Blood Raven (example) would be awesome.

I love the hidden skill idea, but it wouldn't really work with a multiplayer game. It would stay secret for how many days? But maybe having some skills get affected by points in others. For example, if you maxed lightning and nova, then lightning's projectile would become more wave-like rather than a straight line.

Level editors would be neat, but if implemented, would have to give no drops or exp. Or maybe "temporary" drops, which only exist in that game. I could imagine somebody making a map full of superchests and Mephisto clones, hence the need to prevent players getting anything from this. XP

[Kaeros]

The new "Synergy Skills" wouldn't be able to be kept a secret for more than few days, and I think it would be a better to idea to have them revealed from the start as grayed out icons.

I like the idea, but there would be a fine line to follow. You would want the skills to be powerful enough to warrant spending X points into their prerequisites, definitely. However, you also wouldn't want them so powerful and cool that everyone plans for them, thus creating a huge sweep of people with the same exact skill choices (which are needed to unlock that new, uber skill).

It's a wonderfully creative idea, but it might be counterproductive to variety.

[ComatoseSoul]

In regards to unlocking new skills; if done right - it could increase variety. I am probably indifferent to whether they are hidden are not (as both of you stated, they would become known relatively quickly ayways.) That said, it could make for some interesting decisions - an extreme example would be current day sorceress.

What if Teleport was an 'unlocked' skill that required 20 in Warmth and 20 in Static Field? It would pretty much be unlocked as max, but you would be forcing decisions. Sacrifice dmg for utility? Or sacrifice utility for more extreme dmg? (20 in each is too extreme, but you get the idea.)

Much harder to balance, but they did say they want to add more depth to the skill trees ;)