I chose the pixeljunk monsters demo. it's only 12.5MBs. the half-life hero demo is 9MBs. and, the smallest I've come across, the evil lord demo, is 6.9MBs. I have one as adrenaline, one as ark, and one as vhbl. I've installed all three on the ps vita as well as the pstv. they require idu mode to install their pkgs as they won't transfer via cma. I used my psp to grab their licenses from the ps3 as well while installing them to the ps vita through qcma. I think these r the smallest demos available or at least that I know of.