Thanks for the kind words!
I am working on a bigger PC version of the game - there is a link to a website in the description. This version will have an endless mode, since it's a really common request among players (though it'll be a challenge to design it properly so it doesn't get tedious).
The development was on a hiatus for a while, but I'm now back to working on Slipways full-time - leave your e-mail on the site if you'd like to be kept up to date :)
IMO the infinite mode doesn't have to be infinitely fun, it's more important that the time limit mode is fun and challenging.
My main wishes for the PC version are for better balance (no dominant strategies), and less luck (some luck is fun, but the web version has too much).
Thanks for the game. The basic mechanism is fun and original, and also a bit nostalgic.