GameBot - Telegram's in-app gaming platform
Tango Card - Tango Card bundles an awesome catalog of e-gift cards and other e-rewards with easy-to-use technology and expert program support.
Facebook Instant Games - Play games right inside Facebook Messenger
Rybbon - Send digital e-gift cards as marketing incentives or rewards with Rybbon, which integrates with Marketo, HubSpot, SurveyMonkey, and Qualtrics.
Imagzle - A (very) hard image based quiz game
Giftbit - Buy, send and track digital gift cards for your reward and incentive programs.