I tried the demo of Tidalis back in the day. My impression back then was that the backgrounds were really pretty, but there were too many options available, especially for a casual gamer. I also didn't feel like the mechanics of the game within the first 5 minutes that I tried it captured my attention more than the countless puzzle games on Kongregate. I did eventually pick up Tidalis on a sale, but I haven't really gotten into it, possibly because I'm not a pure puzzle gamer -- I need some non-abstract context in my puzzles. Also, I don't know how it was back when Tidalis was released, but the genre is completely saturated nowadays given all the iPhone apps. Tidalis most likely belongs on the iPhone, but the chances of success are slim.
In general though, I think minimizing the effort of trying out a game (via a web version) is a huge win. This is especially important for a game that doesn't seem so compelling from screenshots, like Shattered Haven. I think the gameplay is very enjoyable, but when I first heard about SH, I thought it wasn't for me. Only after trying it out did I get to like it. It's essential to get people to try out a game like SH -- I think that's the only way to really get sales. Even for SC though, which is a game with several very strong concepts, giving people a way to try the demo without the barrier of first having to download and install it (ie just click and you can play) is a huge plus. If you have the ability, it's a shame not to use it.
In general, my opinion is that indie games can only really thrive if they offer a twist that you can't get anywhere else ie. they really excel at some unique aspects, or if they serve a severely under-served niche. There are too many games available (especially nowadays, when all digital games ever made are competing at ever decreasing prices) for indie games to stand out unless they truly do something special. While SH is a very fun game, I don't feel that it does anything that stands out from the crowd -- it does a whole bunch of things quite well, which is enough to make it a very enjoyable game, but it doesn't stand out in my mind as being 'mind-blowing', and that makes it a hard sell. The game will certainly gather its group of fans (myself included), but it'll be very hard for it to thrive.
I think the evidence from AI War and SC suggests that Arcen has the best chance of coming up with truly innovative, exceptional titles around the strategy genre. Other genres, including 2d platformers, are not only crowded, the standard has been set so very high in terms of animation, art (even by small indie teams), and gameplay twists, that it's very hard for you guys to compete there. BTW in retrospect, I think Valley2 should have used easy-to-make, pixellated graphics, which would have been easier to animate well (and would have required fewer frames). I think this is why companies stick with the genres they've done well with before -- it's where they have the competitive advantage in terms of infrastructure, knowledge, ideas etc.
BTW I managed to get past the problem with Arlene. I kept talking to her with 'use', which brought up the same conversation. Bumping into her, though, led to her giving me the key. Really enjoying this game as well as SC!