If you added UrbanFanatics' source and installed, and you're running an iPhone 5S (and maybe the 5 as well), you likely crash back to the homescreen every time you launch ScummVM.
Fear not, there is a way to make this work, you'll be up and playing awesome 90s adventure games quicker than you know it.
Requirements:
a) Some way of copying files over to your device, outside the sandbox. This can be iExplorer, SSH, iFunBox, DiskAid, whatever. You just need to be able to do it.
b) You need an internet connection. Derp.
c) You need some ScummVM roms.
How-To: 1) Install ScummVM from the UrbanFanatics source. This means add the source if you haven't already, it's a package in Cydia.
2) Download the latest nightly development build from the ScummVM Build-bot. Link available here:
http://buildbot.scummvm.org/builds.html
3) Extract the .tar.bz2 you got until you've got a ScummVM.app folder and its contents.
4) Rename ScummVM (the application file itself) to ScummVM-old
5) Rename ScummVM-iph5 to ScummVM
6) Connect to your iPhone and copy the contents of the ScummVM.app folder to /Applications/ScummVM.app (aka /private/var/stash/Applications.XXXXX/ScummVM.app
7) Disconnect your iPhone, launch ScummVM from the home screen.
Now it should run instead of crashing to the homescreen repeatedly. Tada!