Focus on broad audience
Typical social gatherings are family or friends oriented. A game that appeals to the oldest and youngest alike can be a unifying force. A very appealing game brings people together with simple intrigue and laughter. Having a fun ice breaker for new people can make them feel welcome in moments.
Lack of exclusion
Adult themed and drinking games that aren’t afraid to “go there” can be entertaining but not for all age groups. Not gauging comfort levels can backfire. Drinking games have an obvious binge aspect that can create cringe at your gathering. These more extreme elements form barriers to inclusion. Neither are a good fit when meeting new people.
Simple and memorable
A great party game is one that is simple enough to explain to the person standing next you in a few minutes. Simple structure, rules and logic make introducing the game to new people simple. This also gives new players a foundation for more elaborate modes of play.
When game play is unpredictable, it forces players to use their senses and wits to win. Having unpredictable endings can make a game much more memorable.
Varied modes of play
Learning more complex ways to play comes through quick understanding of the basic rules. Having increasing difficulty creates modes of play people are familiar with from other games. Playing as teams or head-to-head Backstabbers is easy once you understand the basic rules.