Try the freeware version of World Creator . WC 2.5 is chargeable but fantastic. You'll be able to make your own tiles and background which are good enough for placeholder if not better.
Placeholder Art? Well if I must...
Miscellaneous Forums/General Discussion/Placeholder Art? Well if I must...The forum is locked. These are the original blitzbasic.com forums, kept so they can still be read. No new topics, replies or edits can be made here. To join in, head over to the Blitz3D+ forums.