Comment by d1zzy

Not if you agree to an EULA that explicitly prohibits it. See https://en.wikipedia.org/wiki/Bnetd#Blizzard_takedown_demand...

And https://en.wikipedia.org/wiki/Bowers_v._Baystate_Technologie....

Note that pretty much any EULA I've seen in the past 10 years has had an anti reverse engineering clause.