Excellent Customizability but quite difficult to learn. You can design planes, boats, submarines, airships, tanks. You can choose the type of propulsion from electric, fuel, steam, sails and you can customize them for fuel efficiency, speed or safety. You can choose the types of weapons you want from customizable missiles, heavy cannons, lasers, spinning rams, suicide bombers. You can then customize the behaviour of the vehicle from having a plane that does bombing runs or you can design a long range gunner which tries to remain kilometres away from the enemy. You can go for extremely heavy physical armour at the cost of weight, electric shields which take lots of power or you can rely on fast speed and flares to distract missiles. There are even spin-blocks which allow you to create segmented vehicles with moving parts for example you can design a bomb hatch which remains closed for defensive purposes when far away but opens up when getting close to enemies. Whilst Vehicle design is complicated it's extremely rewarding and nothing is more fun than seeing a vehicle you designed work as intended and seeing it battle.

Out of all the vehicle building games FTD has by far been the most enjoyable and fun and some of the vehicles people create are truly insane.