I'm Mark, soon to be writing this from Cyprus. After a career in London Underground operations, then training delivery and design, I now spend my time making browser puzzles, an iPad colouring app, and whatever catches my interest next. Everything here is made at home, free where it can be, and honest about what it is.
Everything here is made at home and tested before it ships. Where an app can be free, it stays free.
Ten browser puzzles that rotate daily — Kurosu, Slitherlink, Hashi and friends, each with graded difficulty and every puzzle proved to have exactly one solution. Free in the browser, with no accounts and no tracking, permanently. The same ten grids are now an iPhone and iPad app that plays with no signal at all.
Read more about puzlr
A therapeutic colouring app for iPad: tap-to-fill vector line art across fifteen categories, mandalas and stained glass through to ocean scenes and space, with proper brushes for freehand work.
Read more about Tintl
A free lucky-number generator with one-tap presets for EuroMillions, Lotto, Thunderball and more, picked by a three-stage shuffle rather than a plain random number. Works offline, no tracking.
Read more about Lucky Dip
A simple weight-training tracker that keeps everything on your device — log the lift, see the trend, no account and nothing sent anywhere. Now on the App Store.
Read more about Iron Log
A reminders app for iPhone whose reminders are real alarms: as loud as the Clock app, straight through silent mode and Focus, ringing until you deal with them. Three intensities, Siri, and one button that silences the lot for the cinema.
Read more about Unforgettable
The project I'm proudest of: a working miniature of the Underground built for operations training, so staff can practise procedures on a railway that fits on a table.
Have a look at the digital tabletop railwayNo accounts, no analytics, no adverts. There is nothing to opt out of.
The puzzles and the apps run offline once they are open.
Paid only where the app has to pay for itself, and then once.
The habit the railway taught: prove it against the evidence first.
I spent my career on London Underground — first in operations, then delivering and designing training across operational roles. The crowning glory was the digital tabletop railway built for operations training, a working miniature of the network to learn on. I retired in July 2026 and kept the habit: everything above is built the same way, checked against the evidence before it ships.
All of my apps are coming to Android soon. Become a tester and try them before anyone else.
Become a testerGot an idea for an app, found a bug, or just want to argue about Slitherlink? I read everything.