You actually bring up a good point, unintentionally (Well, the thing about the portfolio is a good one too): The platform really depends on the game. I mean, there are some things that just don't work with Flash. No one wants to sit down and play a flash-based RPG, for example. Something like Tactics Arena (
http://www.tacticsarena.com/) works great in Flash though. Downloadable games have a wider variety of things that work.
So, I've got a few ideas, and I figure I should outline them, and people can make arguments for the platform, and design of the game.
The first is actually a game similar to Tactics Arena, but with greater variety, and greater customizability. If you play a few rounds of Tactics Arena, you'll notice it gets stale as there's no real variance in the game play, except for how you place your units. I want to fix that.
The second is an idea that I got after reading someone comment on Homestuck, when they got the Gab Badge, or whatever, "Of course it's not a game where you get the ability to talk at the top levels. That would be stupid." Well, call me stupid, because I think there's something to be had with an idea like that, where the player gains what we think to be basic tenants of gameplay, as skills when they level up.
The third is a weird sort of idea that's been half-formed and kicking around in my head. It's a game that I've only got the ambiance really designed for, I know it'll be a side scroller, and it'll be about a reporter, and it'll be black and white, with flat colors or a newsprint texture, but not much more about it.
Click for images