Considering I’m not really one who pays a huge amount of attention to illustrations (that’s not to say I don’t appreciate them, but they tend to be background details of a larger whole rather than individual pieces of art I appreciate separately from an RPG product), this is surprisingly hard to narrow down.
However, NPC isn’t an RPG per se, more of a GM tool, an RPG accessory, if you will, so I’ll skip it for this one.
I find myself torn between a few RPGs, some of which aren’t even released yet. One I’ve been watching for a while with anticipation (and the hipe they will release an English translation) is Degenesis, a post-apocalyptic RPG. The artwork in it is stunning and from what I’ve read about it so far, I’m extremely interested. However, it’s really hard to pick a favourite bit of art from it, and since it’s not released yet, there is certainly unrevealed artwork which I haven’t seen. Therefore it’s somewhat difficult to pick a favourite from it.
Scavengers has fantastic, fun artwork in a cartoony style that really sells the mad-cap looting atmosphere of the sci-fi RPG focused on salvaging spaceships for profit. Again, it’s not released yet though so it’s hard to pick a favourite without seeing everything.
Following the cartoony illustration theme, I think my favourite probably has to be the illustrations from Do: Temple of the Flying Pilgrims. Like Scavengers, the artwork really speaks from the heart of the game, giving you a feel for what it’s about and the kind of fun you can expect from it. My favourite piece in particular is only shown (albeit only as a small image) on their website. I think that piece in particularly was done by Liz Radtke.
Honourable mentions go to Kieran Yanner’s work on Numenera. I think the cover illustration of the Numenera corebook really collects a number of things about Numenera in one place that make it what it is and presents in a cool almost movie poster-style way. I really like the art style as well, but in the end Do’s artwork won out.