Warren County, Mississippi, May 19th, 1863. Battalions of Union soldiers march through the marshy ground of the delta, the wet slop already clinging to their boots. The morning chill is already passing, promising to leave a parting gift of southern humidity as the summer sun climbs over the grassland to the east. The soldiers, low on spirit but not resolve, check their rifles and equipment as they advance to the siege lines of Vicksburg. The morning would almost be peaceful, were it not for the hissing and clanking of three 10-foot steam-powered walking robots armed with cannons and enormous sabers sent to bolster their ranks.

Such is a typical scene from Ironclad Tactics, an American Civil War strategy game that has nothing to do with the Monitor or the Virginia. This lane-based tactical card game was first introduced on Steam, where its unconventional setting and odd mix of real-time lane based combat and card strategy have won it a few fans. The basic structure mixes lane-based games like Plants vs Zombies with a collectible card game: while the action plays out in real time, you'll still have to wait for action points to accrue before you can deploy units, weapons, or movement modifications. The core of the game revolves around the steam-powered Ironclad automatons, possessed by both the Union and the Confederacy in this alternate history, though you'll be able to play more conventional soldiers as well.

Trailer from the original PC version. Aside from some scaling and touch elements, it looks exactly the same on my G Pad 8.3.

The primary campaign follows the Northern inventor of the Ironclad system and his apprentice as the War Between the States begins. The story plays out in various comic book panels that are surprisingly light in tone given the subject matter. Cards are unlocked through the campaign, and can be upgraded and combined into custom decks. Ironclad Tactics comes from developer Zachtronics, which previously released the sci-fi puzzler SpaceChem as part of the third Humble Bundle.

The app description says that there are "no ridiculous in-app purchases," despite the fact that Google's system marks the free game as including IAP. I've downloaded the game for my tablet and can't find any store or currency options, so I'm guessing that the IAP comes in the form of the expanded story that's already being sold as DLC on Steam. I assume you have to play through the main campaign to see these options. (I've tried the first few levels with no interruption, so it looks like you get a good bit of content for free.) I've reached out to the developer for clarification.

Update: developer replied to my inquiries. The full game can be unlocked after the first six levels for $3.99, including the full campaign and new game plus mode. Two add-on DLC campaigns are available for $2.99 each.