1x27 - The Melancholy of Haruhi Suzumiya

The Computer Research Society challenge the SOS Brigade to a computer game they created for the cultural festival, The Day of Sagittarius III, demanding their computer back from Haruhi should they win. During the contest, Yuki finds out the Computer Research Society cheated by disabling the fog of war on their side, and hacks the code to restore it, resulting in the SOS Brigade's victory. Awed by Yuki's hacking skills, the Computer Research Society invites her to spend time with them.