Marketing gamification is what it sounds like - you use games in your marketing strategy to engage with your audience.
Games can range from quick social media polls to complex apps and contests. It doesn't have to be expensive to be great, though.
The key to a successful gamification strategy is creativity.
You can use marketing gamification on many different channels, including your website, your emails, and on social media. On social media, specifically, you can even take advantage of some built-in features, like Instagram and Facebook's interactive stickers.