Which engine and ROM should my bot have?

Both live under CPUs, engines and totals, the second row of the Factory's Stock parts. Click the row to open it. Drag an engine onto the Engine bay, or a ROM onto the CPU socket under the chassis. Neither can be taken off, only swapped, and neither uses a mount or a channel.

Engines

There are three engines for ground machines:

• ENG-S: the lightest and weakest. Every chassis comes with it.
• ENG-M: more force for a bit more weight. It keeps a loaded medium chassis moving.
• ENG-L: the strongest and heaviest. It gets a heavy chassis going, and makes a light one very fast.

Top speed and acceleration come from the engine's force divided by the whole machine's mass. Every part you add slows the bot, and a bigger engine wins the speed back. Engine power also affects how steep a slope the bot can climb.

An engine doesn't change how fast the bot turns. That comes from the chassis. Drones and gunships fly on their own rotors (ROT-1 and ROT-2), so they don't take an ENG.

Watch out: a program tuned on one engine can overshoot its turns and targets on a faster one. Test again after you swap engines.

ROM

The ROM is your program's storage space:

• ROM-S: the standard size. Every house bot fits in it.
• ROM-M: twice as big.
• ROM-L: four times as big.

The Factory's Totals show the ROM size in words, for assembly and for the other languages. A bigger ROM doesn't give you more CPU cycles per tick or more RAM. Those are set by your program's league. If your program is bigger than the ROM, it won't load onto the machine, and a program written for a bigger ROM won't fit a machine with a smaller one.

How to choose

1. Build the machine with ENG-S and ROM-S.
2. Open Totals and look at the top speed, acceleration and climbs (soil). If the bot is too slow, try ENG-M, then ENG-L. A coloured number shows how much each total changed.
3. Change the ROM only when your program won't fit.

Hover over any engine or ROM to see its exact force, weight or size.