Text copied from Clive Brooker's website:
http://www.autolaunch.co.uk/spectrum.htm

Boat Run

Copyright Simon Micro-Soft 1983 (Unpublished)

This program must be run in an emulation of a 48K Spectrum.

From computer game magazines of the time, it became clear that it was no longer possible to sell software written in slow Sinclair Basic. It had become necessary to write code that directly drove the Z80 CPU, affectionately known as machine code! Pure machine code is simply a series of numbers (0-255) that manipulate the Central Processor Unit. As a novice, it is a difficult language to learn and Boat Run was to be my first attempt at moving a small portion of the screen as fast as I could.

The space key starts the scenery moving horizontally, with the W (up) and Z (down) keys used to navigate the boat. The objective of the game is to get to the end without crashing. Not a very good game, more an attempt to write Machine Code that worked.