I have used most of the games that I play with children with adults. It depends very much on the group of adults.
1. I have played run to the board to choose one of two word games.
2. I have played a game with first conditional that can be adapted to certain other grammar. First split the group into 3 teams (5, 7... it works best with 3 but any odd number will work). Each team starts with 3 points. If I have 3 groups, I start with two pieces of paper. I write a first conditional sentence on the top of the paper (something simple, for example: If it is sunny, I will go to the park.) The students must take the independent clause, make it dependent and start a new sentence. In other words, they must take "I will go to the park" make it "if I go to the park,..." and finish the sentence. As soon as they finish the sentence, they pass the paper to the next team. If one teams ends up with both papers, they lose one point. Continue until only one team has points left.
3. Jeopardy, Soccer (from mes-english.com)
4. This is not a game, but many adult students enjoyed this. I wrote questions from
Conversation Questions for the ESL/EFL Classroom (I-TESL-J) on index cards or strips of paper. I started off every class by giving each student a different question. They then had to pair up and talk about their questions. If possible, I tried to use questions that reviewed the grammar of the previous class or previewed the grammar of the current class.
5. One student comes to the front and sits with her/his back to the board. I write a sentence on the board. The students in the front cannot turn around and look. The other students must communicate the sentence on the board without using any word that is on the board. For example, I write "I eat pizza every day." Most adult groups go in order of the words. Starting with "I," they give hints such as "not you," "you, name of the person in front," "the letter between H and J," etc. They get very creative!