Time-lapse of TwistedCoverLogo, by Prowler.
It shows the image is made 1/3 with pencil&paper, 1/3 in grafx2, and then 1/3 in Photoshop for further digital work.
Bonus: the working step images (including the final cover).
A rather nasty bug has been identified in the 2.4 release : Unless you're in Layers mode, the palette operations X-Inv, X-Swap, Reduce and Sort are not undoable (issue 514)
I've uploaded new builds that fix this problem as well two others much less severe. Sorry for the inconvenience.
Making-of No Escape, from pencil to composition (and a few vector effects) in Photoshop and pixelling in Grafx2.
It seems Prowler was using Grafx2 v2.1, judging by classic skin and no layer toolbar - two layers would have helped him draw over his sketch and fill his clean outline without having to clean every pixel of the sketch. He doesn't use the Shading mode as I'd have thought, instead I suppose he uses a lot the keyboard shortcuts for next/previous color : [ and ] on a QWERTY keyboard.