Experiences with RetroArch on the aging Xperia Play device can be best described as mixed. I have one which I use purely for emulators and have found it so much better since I abandoned the stock ROM in favour of Cyanogenmod 10 (Android 4.1.2 Jelly Bean). This is not available from the Cyanogenmod site but can be downloaded from the Free Xperia project:
https://sites.google.com/site/projectfreexperia/download/cyanogen-mod-10
When I installed RetroArch 1.0.0.1 on the stock ROM, many of the cores were not available. I’m not sure why this is, assuming they weren’t built with Gingerbread (remember that?) in mind. I also tried Cyanogenmod 9.2, but there were a few issues (forget what they were, may re-test). However, the Play seems to hold up quite well CM 10. To my surprise and delight, most cores run beautifully at full speed without a single tear, skip, or pop.
The following cores worked seamlessly with all the games I tried:
FCEUmm Gambatte Genesis Plus GX Mednafen PCE Nestopia Picodrive Stella
The MAME 2003 and FBA cores also ran the majority of games at full speed, although some (CPS1 games for example) ran faster on FBA than MAME and for some the reverse was true. Notably the SNES and PSX cores struggled, but could achieve full-speed by overclocking the Play’s CPU to 1.4 GHz (I do not personally recommend you do this). Seems ironic because the native PSX / PS One emulator were an original selling point for this device (Crash Bandicoot was pre-loaded). As it turned out, the number of PSX games available from Sony’s app. store was pitiful. No Tekken?!
Anyway, my point is I have never seen the Xperia Play working so well with the older systems before (I am a big Megadrive / Genesis and PC Engine fan). I would be interested to know if anyone else is running CM 10 on the Play and their experiences with other versions. I am really enjoying mine again, having almost consigned it to the bin. I may write a longer article about this if there any interest.