To install mono-runtime just follow these instructions.
sudo apt-get install mono-runtime
Which will install mono-runtime and any other packages on which it depends.
|Maintainer||Debian Mono Group <email@example.com>|
|Description||Mono runtime - default version ECMA/ISO Standards. Mono is an open source effort led by Xamarin. Mono provides a complete CLR (Common Language Runtime) including compiler and runtime, which can produce and execute CIL (Common Intermediate Language) bytecode (aka assemblies), and a class library.|