We have services agreements with the League of Legends and RuneScape developers, and we run 1 ad (below-the-fold, not in EU/UK) on the RuneScape wikis. This covers all expenses (including 5 staff) by a pretty healthy margin

It is described in the linked article.

> The company primarily relies on three streams of revenue: user donations, serving ads on select Weird Gloop wikis, and a contract with Jagex that includes a fee to cover hosting and administration costs.