Today I learnt that BBC kids had a weird knock-off of Boulder Dash called Repton instead of a weird knock-off of Defender called Repton. :)

(Wikipedia claims that Beeb Repton was built entirely on the description of Boulder Dash found in a review, rather than actually playing Boulder Dash.)

This is going back a fair few years now, but having played both, my recollection is that Repton is a bit of a different game. The diamonds in are always stationary, and everything else runs in lock step, so there's no chance of outrunning the rocks or the scrolling.