I am developing a game and I am particularly interested in a Bastion-like mapping style. This is a good shot:
I am unsure about how to achieve that. Currently I use both Photoshop and Illustrator. Any ideas?
You certainly could do this in Photoshop. Bastion was more likely done in Painter 7, from Procreate, since that seems to be the preferred software of Jen Zee, lead artist on the game.
Regardless of the software you use, you can find many artists sharing their tips and techniques to make digital paintings around community sites like "CGSociety.org". Or if you're ready for a flood of information, straight up googling "digital painting tutorial" brings back TONS of links.
The texturing or graphics look like they are hand painted, so you would need to use a software capable of digital painting, like Photoshop, or as someone mentioned Painter. You can get soft gradating effects in illustrator but it really is not suited for this 'painterly' style.
I have never worked with this style or angle, but i believe this is an isometric angled view so maybe look into tutorials on how to achieve this effect in either 3d software with textured polygons or using 2d graphics and tiling etc. Illustrator does have an easy way of creating isometric angles, using the Extrude and Bevel tool in the effects menu, but you would still need digital painting to achieve the painted 'style'.