To date, empirical research relating to responsible gambling features has been sparse. A Delphi-based study rated the perceived effectiveness of 45 responsible gambling (RG) features in relation to 20 distinct gambling type games. Participants were 61 raters from seven countries and included responsible gambling experts (n = 22), treatment providers (n = 19) and recovered problem gamblers (n = 20). The most highly recommended RG features could be divided into three groups: 1) Player initiated tools focused on aiding player behavior; 2) RG features related to informed-player choice; 3) RG features focused on gaming company actions. Overall, player control over personal limits were favoured more than gaming company controlled limits, although mandatory use of such features was often recommended. The study found that recommended RG features varied considerably between game types, according to their structural characteristics. Also, online games had the possibility to provide many more RG features than traditional (offline games). The findings draw together knowledge about the effectiveness of RG features for specific game types. This should aid objective, cost-effective, evidence based decisions on which RG features to include in an RG strategy, according to a specific portfolio of games. The findings of this study will available via a web-based tool, known as the Responsible Gambling Knowledge Centre (RGKC).