I have the old Planetary Empires set for using in 40K campaigns, however, the set only contains random landscapes and Imperial ruins. For our dynamic campaigns, I am making simple faction specific tiles for some of the major armies.
Here is the first set of Tyranid tiles. This set includes three different types of capillary towers, and two different types of digestion pools. For our campaigns, as the Tyranids advance across the landscape we swap out normal tiles for Tyranid themed ones to represent the creep. The towers and digestion pools can be used for Tyranid specific bonuses as opposed to GW's very basic use of Imperial structures, which made no sense thematically. Enjoy!
(There are two files I remixed in here that I can't find the originals for: The three spires over the pool and the digestion pool with the tentacle sticking out. If anyone happens to know, just throw them my way and I will link them for their due credit!)
Uncle Jesse's Gunmetal