This app was mentioned in 2 comments, with an average of 2.00 upvotes
Ah ok, thought you saying that one d4rklord mentioned was too bleak.
One of these?
Defense Zone (https://play.google.com/store/apps/details?id=net.defensezone.first&hl=en)
Nexus Defense (https://cdn.soft112.com/nexus-defense-desert-storm/00/00/0F/P9/00000FP9L8/pad_screenshot.jpg)
One of the Sentinel games, 2: (https://www.origin8.com/screenshots/sentinel22.jpg), 3: (https://play.google.com/store/apps/details?id=com.Origin8.Sentinel3 )