Space Rocks predates the Harmony Encore and was written using a version of the DPC+ driver which has a bug in it which prevents it from working on the Encore. batari released the 1.06 BIOS which will allow the Encore to run Space Rocks, however it's for NTSC. I was contacted yesterday by somebody in Europe who wished to run Space Rocks, but didn't wish to use the NTSC BIOS.
I took a look, but am not able to rebuild Space Rocks at this time because the Linux Virtual Machine I was using to compile the C code was corrupted during an update to Parallels (which is why I now use VirtualBox).
I then remembered I'd helped spendidnut with Chaotic Grill(a very impressive port of BurgerTime). He'd been using a really old version of the DPC+ driver with a bug in it that would crash the program under certain conditions. I was able to replace the driver in his ROM without having to recompile.
So I've run the following via Terminal on my Mac (these commands also work under Linux) to replace the DPC+ driver used in Space Rocks:
dd skip=3 count=29 if=spacerocks20121129_NTSC.bin of=srn29K.bin bs=1024
cat DPC+20121020.arm srn29K.bin > spacerocks20121129_NTSC_encore.bin
dd skip=3 count=29 if=spacerocks20121129_PAL.bin of=srp29K.bin bs=1024
cat DPC+20121020.arm srp29K.bin > spacerocks20121129_PAL_encore.bin
It can now be used on the Harmony Encore running the 1.05 BIOS.