About a year ago, my brother turned me onto a great computer game called
Slay (available
here) by Sean O'Connor. The game is basically a territory-capture game with different ranked units and an underlying economics system. It's got a set of rules that are very much like boardgame rules, and it plays out on a hex map. Although it has a boardgame feel, I think it works much better on a computer than it would on a board because of the underlying mathematics involved - the math isn't so hard that you couldn't figure it out, and you can actually do the calculations if you need to for a critical decision, but mostly it's more fun just to let the computer do the math and focus on the strategic parts.
And the strategy is fun - you've got ranked units that can capture territory or block others from capturing, and buildings that merely block capture. You do much better with bigger connected areas of territory, so the idea is to consolidate from small dispersed areas into a large area whose edges you can defend. Each separate territory you control has its own economy, so small areas can't afford very powerful units, while with bigger areas, you can get some of the more powerful units that can defeat lesser units and take out the buildings. Also, your guys can move to and attack from any space in a connected territory, so units fly around the board if you've got a big connected realm. The catch is that you have to support the units (but not the buildings), so you need to have enough squares under your control to pay all your guys each turn. If you don't they ALL die, not just the ones you can't afford, and your territory is up for grabs unless you've got buildings in place. The unit costs go up exponentially for the higher ranked units, so they can be dangerous. Any spare income you don't use is banked, so you can save up over the course of several turns, but your reserves are lost if your area capital is conquered.
Further complicating the game are plants that grow into spaces and cancel the income you receive from them. There are two kinds, one of which is a pine tree, which grows slowly at apparently random intervals, while the other looks like palm trees (although when I'm playing I think of them more as weeds). The palm trees spread each turn to an open space, so you can rapidly lose territory to a weed infestations. You can clear a square with any unit, but that counts as the unit's attack for the turn. When units die from lack of support, they often turn into weeds (conquered buildings sometimes go to pine trees), so a bad economic defeat can cripple a whole area and then bleed over into neighboring territories.
The strategy is interesting - you want to try to expand and connect your areas, but you also need to defend, particularly when you've got a narrow strip of territory that could be easily severed. Often, late in the game, you can pull dramatic moves, sending a string of guys across a big area to divide it into two, which can cause somebody's whole army to die all at once. But doing that can leave you unprotected, so somebody can do it to you right back.
You can play online with others, but the network interface is pretty old-school, so I've mostly just played against computer opponents, who are quite competent and fun. The graphics hearken back to simpler 8-bit times, and it's clearly a one-man operation, which I'm quite familiar with through my experience writing and selling
Snood. The game costs $20 for Windows and Mac, $4 for iPhone, and it's well worth the investment.
Image above borrowed from the Slay homepage.