Gremlins have infested a building site and it's your job to keep them skyscrapers going up and sort those Gremlins out. Viewing your character side-on in 2D, you move round the site picking up and then placing vertical girders and planting horizontal blocks on top. At least five consecutive blocks and two vertical girders make up a floor and as you progress through the game the number of floors you are required to build increases.
All the equipment is delivered by a crane from the top of the screen, including your sandwiches and Thermos flasks which you need to pick up to retain your energy. Then there are the Gremlins: the first few you meet simply fall out of the sky and are relatively harmless unless they happen to land on your 'ed.
Later in the game, the Gremlins start to eat the floor blocks and some just stand around waiting for you to bump into them, removing one of your lives. To counter some of the Gremlins, you can lob spanners at them, but this doesn't work for all Gremlins: some simply deflect the spanners, knocking you out.
High Steel is a disappointing start for Screen 7. It's all nicely done, but the actual concept and gameplay is like something from five years ago when the Spectrum was still a fashionable machine.