Decimal Clock is a simple app which displays an analog decimal clock, with the decimal time in digital underneath, on a green background with diagonal stripes. There are no other options or features. There is a 10 at the top of the clock, as with French clocks, but the digital display starts at 00.00.00, except a brief moment when it says 10.00.00. The app costs $0.99.
There's an ad that's one of those autogenerated videos like that GEICO commercial at www.headoverflow.com.