It does indeed seem like DC:SS tiles are being used in that game. There are a couple of ways of looking at this.
1, ask the store to take down the game, it's using for profit art from a free game.
2, ask the designer to change the art from what it currently has.
3, intimation is the sincerest form of flattery, be pleased that someone thinks DC:SS tiles are good enough to use in their own game.
4, DDoS the site. Illegal.
And by the way, what is the license for DC:SS, I can't find it anywhere.
The smartest options is too write a letter of complaint to the designer and store.
The Trogyist options is the DDoS attack.
Edit, looking at the devs site he recognizes the tiles are from DC:SS provides a link to this site and says thanks to the community for making such great art.
http://www.seramygames.com/contact.htmlEdit of a edited post. I just sent a e-mail to the dev requesting that they at the least provide a link to the DC:SS home page on the android store or create their own art. Very polite, just letting them know that it's a little bit rude to take something from a free game and sell it without showing right away that this isn't purely original content.