Block-Aid is a mix of puzzle / strategy.
Enemy units race down towards your defenses, you have to move your own units to intercept them before they can get past your last line of defense and lose. Rock, paper and scissor type of fighting, swordsman beat spearman, spearman beats horseman, horseman beats swordsman.
Story mode provides 25 levels of challenges with special unit bosses every 5 levels.
Survival mode pits 15 random units against a never end string of enemies, survival time is logged and kept on a leaderboard (available in game and on the site)