What is your view to code game logic in external language specific to logic , the kind similar to first order logic . In recent years there is much progress in standarizing logic programing using ASP programing == SAT solvers , there is even a standard language for diffrent implementations : the AnsProlog http://en.wikipedia.org/wiki/Answer_set_programming .
There are numerous tools which translate they own event calculus language to AnsProlog : http://www.cs.utexas.edu/~tag/ccalc/( bottom of the page) .
Wiki page on event calculus is quite obscure , intro for event caculus is : http://www.doc.ic.ac.uk/~mpsha/ECExplained.pdf
Most of the ASP solvers publich they code under GPL license so we could make separate module/threat/object for event processing during run time .
The only problem is whether Scenario/Map makers would use it .... most people can program Prolog, and Event Calculus would be a bit harder ... so ?
Here are some programs in ccalc , a specif event calculus language http://www.cs.utexas.edu/~tag/ccalc/examples/