Throughout the last 35 years, there have been two totally rewritten version of Rock Crush, both by the original author.. Neither of which I may add are still availalbe at this point in time. However, this page delves into their history.
The first was for Windows in 2001. This version added a pixel perfect ZX81 emulation mode as well as a re-imagined colour and sound version. There was a also a similar rewrite at this time of Dan's Revenge. The levels were doubled from the original 10 upto 20. A note about this re-imagined colour and sound - I was thinking how it would look and feel heaven forbid, if it had came out on the C64 of all computers! I liked it anyway!
Next, in 2011, a second rewrite brought Rock Crush to the iPhone and iPad as well as Mac and Windows versions. An unreleased Android port was also made. This new 2011 version featured both modes from the 2001 version as well as a brand new modern looking 2014 graphics mode.
Again more levels were added up to 40.
A later major update to it also allowed the ability for the first time to run down from under rocks - after checking it didn't break the gameplay of all the existing 40 levels. 10 New levels were then added that specifically needed this ability for you to even solve them!
All of these levels and a few design changes (such as being able to run down underneath rocks and the warp zone idea) have made it into the new 35th Anniversary Edition on the ZX81. A new ending screen has also been added in.
Re-imagined ZX Spectrum style colour was also added to this version thanks to suporting the CHROMA Colour Board (See Links page for more details on this).