"xmlsh" is derived from the design and goals the unix shell and core commands but with XML expressions and documents added as core features to the shell. xmlsh can be used as a drop-in replacement for scripting xml transformations instead of sh.
Virtual machine implementation for visual novel games
ViLE is a collection of interpreters capable of decoding visual novels and dating sims. You can use ViLE as a drop-in replacement for the original executable to play the games, but ViLE also provides exclusive titles and features such as software scaling.
Senora is targeted to be a drop-in replacement for sqlplus. It provides a plethora of new commands, which accept unix-style options. It is extensible via plugins.