If you took Plants vs. Zombies, replaced all the zombies with armed peasants, replaced back gardens with the fantasy world of Beneril and orbs of sunlight with sweet gold, then you'd have something similar to the horribly addictive, free to play browser game Warlords 2 .
The key difference is that in this analogy, you control the zombies. Waging war in Beneril means politely sending troops one by one down a series of lanes towards the enemy. You win by getting a certain number of warriors to the other end of the screen, which will mean overcoming the defensive forces marching the other way. Every unit has its weakness. Archers beat heavily armoured Halberdiers, Swordsmen chop down fast paced Spearmen and mounted units can clear entire lanes with a well timed dash. Gain enough momentum and you can unleash a charge attack that fills every lane with a unit of your choice, often breaking the deadlock in close contests.
Win a battle and you'll loot some coin, which can then be used to upgrade the speed, armour or effectiveness of your individual units, or buy entirely new ones to give you more flexibility in the next fight. With the day won, it's off to the world map screen to choose which province you conquer when. For the more heavily defended countries, it's worth holding back for a while to buy some specialist siege machines, or at least hire some blokes with ladders so your other troops can scale the walls.
With ten races and 54 units to play with, there's a deceptive amount of depth to Warlords 2. Once I started the campaign, I found it ridiculously hard to stop. All I wanted enough was enough gold to buy the next unit. I'm only one hundred gold away from being able to hire a 'Scythe Whirler', which is exactly what you don't want heading down a narrow lane towards you.