I don't think 1MB is enough to make an RTS game anything great. It's just not enough Ram.
I remember playing Dune 2 on my A500 with 1MB RAM and was really frustrated at the way it slowed down to a crawl everytime more than 1 unit was on the screen. Then i watched it on a friends PC with 8 MB Ram and watched it fly!
I'm sure it may be possible to get around this somehow but does it have to be only 1 MB? I'm pretty sure most people who would play this 1MB RTS game who have classic Amigas to play them on would have expanded and upgraded them significantly with more RAM and faster CPU's enough to make a 1MB benchmark seem small minded. And you know the year is 2011 and not 1990. In 1990 1MB was a good target to aim for but in 2011 i think we can be a little more ambitious than that. What about 8MB running 25Mhz?
I don't see the point in limiting new games to OCS or ECS. It wouldn't hurt or be too hard to put more colours and a higher res in there. Especially after seeing the fantasic glow icons being made.
Just my opinion
there are plenty of games out there for machines of higher caliber. If anything, I would love to see some retro action. I have a friend whose autistic son does nothing but write super mario brothers levels in assembler. Considering that most Amigas out there are classics I would think that should be the market to hit (assuming that this project is all about the fun and learning aspect). I'm all for an AGA option or 2M capable, but I am sure there are ways to make a great RTS work in 1 meg. I just don't want anyone not running a Voodoo3 in a 1200T or 4000 with mediator to be excluded.