NOTE: THIS IS NOT ANNOUNCEMENT FOR A GAME, THIS IS MY IDEA (SORRY)
Personally, like many anime, Zero No Tsukaima has potential for a video game adaptation beyond the usual visual novel. Personally, I envision a sort of open world video game, in which the player, controlling Saito, can roam Halkegnia, take on various main and secondary quests. Depending on the player's actions, different endings can be unlocked, including different "routes" for the female characters. While Louise's route will roughly follow canon, the player can also follow other "routes" with an original plot, both involving pairing with other female characters in the series, or Saito running off on his own.
Gameplay[]
In terms of gameplay, given the 16th century technology level of the setting, I see it as most closely resembling the Assassin's Creed series, with combat using Derflinger and other melee weapons being similar to the Assassin's Creed games, while long range weapons will behave more similarly to third person shooters such as Gears of War. Most of the weapons will be 16th century-level Halkegnian weapons, including swords, axes, maces, polearms such as spears and halberds, bows and crossbows, flintlock muskets and pistols, and black powder grenades.
Weapons and vehicles from Earth will be rare and often found in optional quests, though some, typically the ones Saito uses in the anime/light novels, such as the M72 LAW, A6M Zero, Tiger tank etc will be found on main missions. Ammunition and fuel (for vehicles, at least on higher difficulty levels) is rare, and thus these weapons must be used carefully. When used correctly, these vehicles can be used to devastate legions of Halkegnian troops. For instance, on one sidequest (obviously on a non-canon route), finding an A-10 and use it to annihilate an entire fleet of airships (something I thought up because of how hilariously awesome that would be).
So, what do you guys think, would you like to see a game like this come out.