PlayPlay.io - Chess and Ping Pong tracking in Slack
Pongbot - Slack bot for ping pong tracking.
Papio - Friendly foosball scorekeeper and stats tracker for Slack
Ranked.Fun - An online leaderboard with your friends for your favorite games (Ping Pong, Foosball, Smash Ultimate, Chess, etc.)
Slack Poker Bot - A bot that turns Slack into a Texas Hold'em client
Cards Lacking Originality - A simple and elegant online Cards Against Humanity clone