I've been playing Helena The 3rd quite a lot in my breaks of video game development working on Ensign-1, and I love it hah! It's a great game to just pick up and play for short breaks here and there.
One of the things I wanted to add to the game, but never got around to doing, is multiplayer co-op and deathmatch. I think the game would be a great contender for both of those 2 features. Imagine playing the through the game with multiple friends or duking it out in a battle-royale, with different kinds of tanks and abilities.
Anyway, if that's something you're interested in, check out our Kickstarter campaign to try to bring the idea to fruition. You can pick up copies of the game for yourself or your friends for quit a low price (assuming the Kickstarter makes it through).
Also, just to recap, here is a gameplay video and review of the game, in case you'd like to learn more about Helena The 3rd before purchasing.