A polar pattern determines how much and from which direction an audio signal will be picked up by a microphone. For gaming, you'll mostly want a pattern that picks up sound directly in front of the microphone (you) and not much else from anywhere else (the environment).
These are the most common polar patterns:
Cardioid: Records in front of the microphone. Perfect for voice-over, vocals, and streaming.
Bidirectional: Captures audio in front of and behind the mic. Ideal for one-on-one interviews.
Omnidirectional: Picks up sound from every direction. Perfect for round-table interviews, but not so much for gaming or streaming.
Stereo: Perfect for ASMR recordings. YouTube 'ASMR' if you want the best example because I couldn't do it just justice.