When I started there was Kerbal Space Program, there was Rawbots (RIP), there was Gimbal, but nothing recent with road vehicles except maybe Gear Up. Things have taken a while (I'm making this mostly on my own), and in the meantime vehicle building games have started to pop up everywhere.

Finally in 2012 I had a good opportunity to just start making it myself. Roboforge showed that building your own fighting machines was doable back in 2001, but it wasn't quite what I wanted. What I really wanted was a game where you designed your whole vehicle and the parts really mattered - and no-one was making it. It was a step up in customisation but a step down from Interstate '76 and the other sweet demo I had of Stratosphere: Conquest Of The Skies in terms of meaningful build choices. Later I played a demo of Lego Racers, and you could totally build your car from the ground up, but I was disappointed that it didn't have much of an effect on the car's performance. Way back in the 90s I played a bunch of Interstate '76, and I loved how you could customise the weapon loadout and various components of your car and it all really made a difference. The Scraps demo is also a LAN joiner, so people can join your LAN game even if they don't own the full game. There's single-player against AI, Internet play (and it's easy for anyone to create a server that'll show up in the global list), and LAN. If you die, you can respawn with any vehicle worth up to the initial scrap allowance. During a match you can also collect wreckage and use it to repair/upgrade your vehicle in-game by using an Evac Pad - so it's possible to build a vehicle worth more than your starting allowance, although purchase and repair costs slowly increase as your total worth increases to prevent a snowball effect. Gameplay is your typical melee deathmatch sort of thing, where you get x amount (chosen by the host) to spend on your vehicle.

There's also a heavy physics basis with weight distribution being a big factor and weapon recoil being a notable point to manage. It's more like building vehicles out of Lego, except you can actually drive them at the end and the pieces actually work. You don't have to wire up components or do anything too fiddly. Most parts are functional in some way (power, cooling, engines etc), and often inter-dependent (like weapons will require power and/or heat management), but I've also tried to keep things fairly simple. Scraps is a vehicle combat game where you build your vehicle from parts from the chassis up.

Spore more vehicle parts mod