Back on the subject of difficulty, I noticed there was talk about having a basic 'you have less/more health, enemies have more/less' deal.
Please don't. While it's a quick and easy route to making the game easier or harder, I've always found it to reek of quick half-measure design.
Personally, I think the best games to do multiple difficulty settings are games by Hideo Kojima (Metal Gear, Zone of the Enders), the Silent Hill games, and the Doom series. Oh, and Ninja Gaiden: Black on the Xbox.
In the case of MGS/ZoE, your choice of difficulty skews the 'rules' of the game more or less in your favour. On the easiest settings in MGS, guards are half-blind, have low attention spans, will overlook things like lockers when searching a room, etc etc. On the highest settings, they're alert, attentive and capable. ZoE did even better. Enemies will behave differently on higher settings. A single 'grunt' enemy will be fodder on a lower setting, but on a higher setting will deliberately hang back near friends and make hit and run attacks, retreating to be repaired if needs be.
No new content, but by changing some behaviour variables, the game feels both fresh AND newly challenging.
Silent Hill gave players two difficulty sets. You pick both the difficulty of combat, and the complexity of puzzles seperately. So someone looking more for an adventure game can play with easy combat (low, weak enemies) and complex puzzles (more pieces, vaguer clues, more complex solutions etc).
And Doom went the 'badass' route. The higher the difficulty setting, the more enemies there were. Pure and simple. Easily done (at least during intial design - harder to add later on), but it's a simple route to providing replay value through multiple difficulties.
NG: Black probably went the most difficult route. On each new difficulty setting, the entire game is 'remixed'. New enemy types, different weapon/item placement, weaker enemies replaced with tougher ones. It meant that each time through, the game felt new AND harder. Always a good thing. It gave the game collosal replay value.
All of these are great ways of doing difficulty scaling. Personally, I'd like to see the MGS/ZoE approach for later updates to Aquaria. If AI variables can be changed, enemies could be made more interestingly dangerous. Pirahnas could move less predictably and faster, or perhaps larger enemy types could have a chance to split into multiple smaller ones on death. Interesting quirks and variants that would keep an experienced player on their toes. Likewise, for lower settings, enemies could generally behave more passively. React a little slower, not 'aggro' until the player is closer. All that jazz.
But this is just my thoughts. I'd love to see some of these elements added by either Bit-Blot or modders.
However, one thing I'd be 110% behind is the idea of new official/semi-official expansion campaigns, as brought up by Alec. A new story, with gameplay shifted more towards story/exporation/puzzling/action/whatever. I'd gladly pay £5-10 for another full campaign with a fresh angle, even if it reused a lot of content from the base game.
While I'm happy with the campaign as it is, I have a friend who was almost scared off the game once she found the Energy form - the whole game got a little too actiony for her tastes, and she mentioned that she didn't really start having fun again until she found the Fish form and was able to use it to avoid combat. Some folks just want a huge underwater world to explore. Others want a world full of fishy-flavoured death lasers and energy shots. I'd love to see a campaign in that vein myself, but I'm a bit of a hardcase when it comes to games.
Whatever Bit-Blot or the mod community come up with, I'm eagerly awaiting the results with bated breath.
