Sonic Mania

In Lava Reef Zone Act 1, you will eventually come across a metal walker contraption sat on a platform near some lava.

You need to cross the lava with it, which is patrolled by Rexon (Purple dinosaur looking thing) and crash into it.

To make the walker move jump on one of the legs of the walker so it moves. Keep on jumping from leg to leg.

To unlock the achievement you need to be moving across the lava using one and crash into a Rexon.

Midway through the Act 1, there is a perfect point where there is a couple in a row next to a walker's legs with a shield box under the legs which you have to go past.

For video guide please watch the video below. Thank you Eurydace for creating it:

This can be attained on the first act of Lava Reef Zone. But before starting, whilst in the Mania Mode screen press Y to bring up the Game Options and enable Debug Mode.

If you haven't unlocked this Zone, to access the Level Select Screen, highlight the save file and hold X followed by holding Start.

When the Zone loads up, transform into a Ring by pressing X and follow the route shown in the video to the area with 2 "Metal Legs". Press A to scroll through the items available until you reach the Starpost. Place it on the level by pressing Y and scroll through again with A until you find the Large Ring and place a few down. Turn back into Sonic by pressing X and collect the Rings and enter the Special Stage via the Starpost. Complete the Special Stage (by hitting a Red Sphere) and return to the level.

To unlock the achievement you need to jump from one leg to the other (which makes it walk) and destroy a Rexon in the process.