Singapore Movies lets you look up movie times and cinemas and covers all the major chains as well as the Sinema@OldSchool.
The interface is somewhat quirky and finding a way to look up movies by cinema is not as obvious as it should be.
When you open the app, it immediately shows you a list of movies currently showing in Singapore. Just tap on any title to get a synopsis and list of cinemas where that movie is showing. Within a movie, hit the "Don't Care" button to see all the times the movie is showing at all cinemas. If you hit "Decide Later" within a movie, you are presented with the option to choose a date to get screening times.
To look up movies by cinema, in the home screen, hit the "Decide Later" button to pull up a list of all cinemas. Get it? Neither do I. It's a sad commentary on the state of movie times apps in Singapore that this is one of the better ones.
Singapore Movies is free. You can download it here.