Planes are extremely susceptible to enemy anti-aircraft fire - which has considerable range - so these need to be taken out with long-range artillery or tank fire. It's an interesting addition to the game's tactical repertoire, and does a great deal to enhance the rock-paper-scissors nature of the weapon balance. It's also tremendously enjoyable, and I defy anyone who's ever even heard of Biggles not to make ACK-ACK-ACK noises as they swoop a Sopwith Camel across enemy trenches, raking infantry with machinegun fire (take that, Von Stalhein).
The fully three-dimensional maps are beautifully rendered and designed - covered in scorched shell holes and ragged ruins, littered with the hulks of broken vehicles and stitched with trenches. Initially enemies will all come from the same source, pouring towards your emplacements along predictable paths and generally directly into the teeth of your guns.
As the campaign advances, however, the battlefields become bigger and more complex, offering several potential routes of enemy advance. These are set for each level, meaning that the tower defence staple of trial and error is still very much in evidence, but troops will make occasional deviations.
Navigating these maps is accurate and easy, with a choice between top-down and positionable camera modes making it simple to switch between the perspectives of general and grunt. Upgrades and repairs are easily performed, too, with the d-pad offering shortcuts to these functions once a unit is highlighted with the cursor.
Every few levels brings an improbably sized 'boss' lumbering from the opponent's war chest, with giant tanks, zeppelins and armoured trains marauding across the battlefield. These take a far greater degree of planning to deal with, and generally require fully upgraded weaponry. This means that you're unlikely to finish them off first time, so you'll probably be repeating their levels a fair bit. This can be frustrating, but Toy Soldiers is always fair and consistent - proper placement and management of your forces will always bring you victory in a logical manner.
There's a generous chunk of content here, with the considerable single-player campaign unlocking the German-orientated "campaign+" upon completion. There's also the option of taking on Elite mode, where none of your towers will fire automatically. This ups the ante considerably - perhaps too much to be genuinely enjoyable - but you can't fault Signal for its inclusion.
Each mission also has a unique target goal, such as the acquirement of a certain amount of cash (earned by destroying enemy troops), or taking out three soldiers with a single bullet, earning a 'Ration Ticket'. Though their collection only unlocks an achievement rather than anything more concrete, they offer useful tactical insights and thought-provoking challenges.
Further to all this is the local and online multiplayer mode. This puts you in control of launching the waves of troops and vehicles necessary to overcome your foe as well as the usual battlefield management. There are new maps to choose from, each with a specific focus on a troop type or assault method, and money earned must be divided sensibly between attack and defence.
Holding Y brings up a menu of three attack options, which change according to the map, and these can be launched at a delay for cash. It's a strangely distanced way of attacking, and doesn't come close to the enjoyment of direct control, but it's hard to think of an alternative. Direct control is still an option in multiplayer, but it's not much use for direct assaults on the enemy toybox, although using direct control fills a gauge, unlocking a devastating artillery barrage once full, allowing generals to unleash a coup de grace when the enemy's defences are ravaged.
Overall, this is a wonderfully detailed and polished piece of entertainment, stuffed full of delightful touches and great ideas like the cogs which spew from your clockwork tanks and horses, or the high-stepping animations of troops on the run from artillery fire.
Its charm, and the very nature of its miniaturised models, lend it a levity which has some dissonance with the subject material, but it's a welcome one, entertaining whilst never feeling irreverent or disrespectful. Jolly gramophone records form an authentic, scratchy soundtrack, and a splendid 'tilt-shift' camera mode allows you to freeze the action and navigate it like a superbly detailed tabletop diorama.
Toy Soldiers is a lot of fun - full of freshness and subtlety. It's certainly the best tower defence game on Live, and for my money it's up there with the best games on XBLA in general. 1200 Microsoft Points (around £10) might be pretty weighty for an XBLA title, but there's a depth of quality and enjoyment here which justifies it in spades.