• Graphics
  • Playability
  • Lastability
FormatSinclair ZX80/81
DeveloperBob Smith
Price£TBA (cassette) or free download
ReviewShaun B

Main review

Cornwall isn’t the sort of place you’d expect to find diamond mines – tin mining is a part of its’ heritage, but in Boulder Logic, our hero, Bradford Walker-Smythe, has stumbled across a vast labyrinth of mines which are strewn with diamonds and hazards in equal measures. And it just so happens that Bradford needs to find the perfect engagement ring to impress his missus Tania. Surely a huge, gleaming ten carat rock will win over her heart, along with the heroics of finding the precious gemstone in the first place. Plus, any unused stones will surely make him a fortune; it seems to me that even if Tania turned down his proposal of marriage, Bradford would become the country’s most eligible bachelors, so it’s a “win-win” situation if you ask me.

So begins Bradford’s quest, with 32 spacious and undiscovered mines to explore, each has a finite amount of breathable air and a set quota [of Diamonds] to grab; once this has been achieved then there’s a small matter of finding the exit to enter the next mine.

Bradford is quite a nimble chap and moves as fast as the rocks (and diamonds) will fall. He also has the strength in certain instances to stop an avalanche, though this may trap him and the level will need to be restarted should that happen. From the second level, perilous roamers are introduced which will be killed if a boulder or diamond lands on them. This will affect the play area, but I’ll leave you to find out how so. There are some other surprises thrown in that may also take a few attempts to fathom, but there’s nothing that can’t be done without a bit of persistence, and each level has an access code to carry on where you left off. If you become particularly stuck, there’s a ‘try’ feature on the start menu in which you may play the level until it is completed, which I’ve found necessary on a few occasions.


Graphically, it’s as good as it gets considering the aesthetic limitations presented by the ZX81 and without using any add-ons or the pseudo-high resolution mode that some games used (most notably those from Software Farmhouse circa. 1984). The game engine is particularly responsive and the difficulty curve is mostly progressive with some well thought-out and designed levels to explore, though it will spike every-so-often.

Each quite sizeable level will scroll on the horizontal and vertical plane until you reach a boundary or wall. Whilst some will have more or less set paths, others can either be completed quickly or explored thoroughly depending on how greedy you are on the diamond collection front. It’s not necessary to collect all of the precious rocks though, and doing so will only eat into your time so it’s often best to find the exit once you’ve bagged the required quota.

Overall, this is a great implementation of First Star’s classic Atari 400/800 game Boulder Dash, and with 32 levels is probably the biggest game ever on the monochrome Sinclair. There are also some presentation niceties, such as the splash-screen on loading and the game over sequence which is a sly tribute to another mine-exploring game from a certain Matthew Smith.

In my opinion, this is the best ZX81 game ever, just beating Bob Smith’s Virus by the finest of margins. Taking the limitations of the hardware out of the equation, Boulder Logic is still a very, very good game and can be enjoyed via emulation – and if that’s what you are looking for, head over to or RWAP Software where you’ll find the relevant information and links. Hard-core fans will probably want to play this on a real machine, and again both of the sites mentioned will help you in this quest. It’s quite simply a delight to play, and certainly one not to miss even if you consider the ZX81 as a quirky relic of a bygone era.