Merge pull request #705 from github/add-game-jam-topic

Add game jam topic

Author: brandonrosage

topics/game-jam/index.md

@@ -0,0 +1,9 @@
+---
+topic: game-jam
+aliases: gamejam
+display_name: Game Jam
+related: hackathon, ludum-dare, global-game-jam, game-off, js13k
+short_description: A game jam is a hackathon for creating video games.
+wikipedia_url: https://en.wikipedia.org/wiki/Game_jam
+---
+Game Jams challenge people to create games within a short period of time (usually over a weekend, a week, or a month), and with certain constraints like limited color palettes, file sizes, and themes.