Courtesy of Play This Thing!: the unimaginatively named “The Space Game”. It’s tower-defense in space!
The curious thing is, I found it more absorbing on a personal level than the average tower-defense game, and I’m not sure why. Usually with TD games I sit back comfortably, enjoying god mode, and not really worrying too much if I lose and have to replay a level. Here, though, I was more invested in my little mining colony. In the final level where the pirates come in thick and fast and my colony gets completely massacred, I had to give up after a couple of unsuccessful tries — it just felt too much like one of those really grim episodes of Babylon 5 where everyone is dying left and right and I cannot make it stop.
But, er, you may not have that same problem! And it’s fun, though not remotely IF-like.
Emily Short's Interactive Storytelling 
I loved The Space Game. And I bet those guys at The Casual Collective will only make it better with time.
Oooh, I loved those episodes of B5. I hope that doesn’t make me a bad person. I like to think it’s because they were the perfect antidote to Star Trek. That’s my excuse anyhow.
Although I didn’t have the same emotional connection you did, I do agree that The Space Game didn’t feel like a tower defense game.
It may have been the freeform space: instead of being given a constrained set of places where you could put units, you had a wide open area to work with. And instead of there being a particular path that enemies trod through invariantly, those enemies could come from any direction — any place outside of your own space.
So when you built your colony, it grew organically, and aside from the asteroids themselves, all the geography that existed was there because you made it. Unlike a normal tower defense games, where your only contribution is to drop a few towers into the village/kingdom/whatever that someone else has already created.
I know what you mean about the freeform use of space, but it’s not unique in this. There are a few TD games that do let you control the path (most obviously Desktop Tower Defense — I prefer this, really, because it adds an extra dimension of strategy); there’s also one I can think of (Super Energy Apocalypse Recycled) that has invaders from all around and also makes similar use of the need for mining and energy for one’s weapons.
But not having to work on a grid is neat, and so is the organic quality of having to maintain an energy connection between stations in order to keep them working.
What a fun little game.
I always wish these nodal space games were 3D…
Conrad.
I was also drawn in by Space Game; I only played about half the missions, but that’s more than I’ve done on any other tower defense game in months. Usually I skip the whole genre.
I think the draw is having a goal besides — before — the evil hordes show up. Building your mining colony is a nice little game in itself; a very easy one, until you realize you have to do it *fast* (on later levels), and then it gets challenging. And when the siren goes off, you’re defending something you built.
(I haven’t looked at Super Energy Apocalypse Recycled, so I don’t know if I’d react the same way to it.)
From above, Space Game is more a scion of the real-time strategy genre than tower defense per se. It’s Warcraft where the “yay I have built” thrill is extended to cover the fighting part of the game as well as the resource-gathering part.
Well, this is what I’ve got:
Make crazy amounts of mineral miners first thing; upgrade your energy sources; and you’ll have enough resources to build weapons when the pirates show up on the radar.
The pirates are kinda dumb, targeting the closest (outermost) targets willy-nilly. So enmesh yourself in a spider’s web of redundant energy relays. These draw the pirates’ fire, like an outer picket, giving you a chance to take them out.
Once you consider mineral extraction and power throughput the top priorities, the rest seems to do pretty well.
Other strategies?
Conrad.
I think what makes it so engaging (compared to a usual tower-defense game) is a combination of the fact that the things you build themselves are subject to attack, and the fact that they’re all interconnected, so everything you built is based off of what you built already — and losing one or two important connections things can potentially set off a cascade of failures. Because they’re so interconnected, building things feels like more of an achievement (everything you build opens up the door to more potential in the future), and having them blown up feels more personal (because everything that gets blown up reduces your potential a little more.)
Just a thought, at least.