Runic Games President Travis Baldree noticed that many of the assets used in that game seemed to come directly from Torchlight.
Baldree brought the asset theft to light in an allegation posted in a forum discussion. He stated, "All of the monster assets and every dungeon tileset, as well as voices, and most sound effects, are direct rips from Torchlight... I didn't see ANY monsters that weren't ours." A side-by-side comparison of many models made by another forum member demonstrates the likenesses.
Baldree also provided more evidence including the fact that many of Torchlight's sound file names are identical to Armed Heroes', including typos. Instead of seeking monetary damages or royalties, Baldree is simply asking that Armed Heroes Online be removed from Apple's app store in Canada and not appear in the US stores.
[Update: An alleged employee of EGLS, the maker of AHO, has denied the theft and suggested the similarities are a result of similar source material.]