Main criticism is that there's rarely a good reason to send out two groups of subs at the same time, but it's also not really a waste to, you're not punished ( I think) but they're also not likely to do anything, so it just winds up being kind of weird. Adding in more monsters, more graphics, and maybe a few more mechanics, would make this a fun little game, but I can't imagine it being stretched out much further than this.