It's called Blooms. I wrote a comparison between Blooms and Go focused on how life works in each.

Check it out. I'd love criticism.

Seems fantastic. I hope Richard adds it to the site!

Thanks ypercube. That means a lot.

I've had a look too and it definitely looks promising. Would love to test it here. :)

Cool. I'm looking for a place to get it implemented online. LG is my first choice but Richard is probably too busy for it. Other recommendations welcome.

It seems more dynamic than Go, extremely tactical on small boards. I wonder how would it be on a big board, what kind of strategy will emerge. :-)

Me too. it's been getting more strategic for me on hexhex5 as i've played more and I'm starting to see through the thicket of tactics. But I probably won't see the full shape of strategy until I get it implemented and a bunch of people start playing.

I met this game on some other forum (can't remember where now) and started playing it with my 10 year old.  She's got a real eye for it and beats me embarrassingly often.  It's a great game and I look forward to playing it with a wider pool (hopefully here).

I would murder someone in a dark alley to get it implemented here, as LG is, for my money, the best abstract game site.

Have you thought about using symbols on the markers, instead of just colors? It looks like you made it pretty colorblind-friendly already, but it isn't immediately obvious that red and yellow belong to the same player.

I have considered it, and did playtesting on the question. I've decided to go without symbols because the only time it's unclear is before a person's first game. For all the playtesters I've questioned, it was obvious who owned what after the first move of the first game, and after that symbols were unnecessary clutter.

But that still means I need to make it more clear in diagrams online, where people will be exposed to the game for the first time. Like, for example, in the image above, there should be a little key indicating which colors go with which. I'll do that when I post images like this in the future.

I would have the classic black and white,

but round and hex stones

Tried it. Did not work. Items of the same color are strongly perceptually bound even if different shapes. It was very hard for players to see who owns what in the circumstance. This works infinitely better in actual play, because color contiguity is the main trigger for perceptual binding.

I just added a player key to the rules page for the game. Tell me if this works for you as a means of communicating online.

A minor interesting aspect of this game is the large size of its symmetry group. As usual for hexhex boards, it has rotational symmetry (6 ways) and mirror symmetry (2 ways). In addition, each player's stone colors can be swapped without changing the game value (2 * 2 ways). In total, 2*2*2*6=48 ways to transform a board.

The consequence is that anyone writing an AI using neural networks can take advantage of techniques that benefit from a lot of symmetry, such as Group Equivariant Convolutional Networks.

That's true. Probably especially useful in this case, because there are other factors that make non-network approaches tricky (which is why the AiAi AI isn't so good)

Looks great

There has been a major reformulation of the rules! See here.

Note: while I wait with fingers desperately crossed to see if Richard will want to implement Blooms here, note you can play it on Board Game Arena. It went live 7 days ago and it's been played about ~3000 times since (!!!). The player pool is really big over there and the best players already quite good.