Take reading the instructions for instance. How do people with limited literacy skills ever read instructions? They don't! Usually someone else does the reading and interpreting. From my observations people in these situations always orally learn the game rules. How to overcome this? I've used graphical cues and PowerPoints to assist when introducing a new game. Also, prior to introducing the game I would develop a glossary of terms related to the game. Students would use an online dictionary to assist with pronunciation and meanings.
Scoring is the most obvious numeracy activity but some games offer a broader numeracy experience, for example: Blokus - spatial awareness; darts - subtraction from 501 and multiplication; Triominoes - addition and subtraction; Monopoly - handling money and operations (+, -, x).
Today's adult classes are all about improving a person's literacy & numeracy to enable them to get a job. How can games help to get a job? First and foremost they assist people to develop interpersonal skills. One critera all jobs require today is - able to work in a team. Yes there may be dummy spits during games, but overall participants want to be involved and usually pick up the dummy and play on. You need strategies to play games and these may include: working from what you have (known) to improve your position (unknown); cause and effect - if you play this card or tile then your playing partners / opponents won't be able to move or play a specific card; problem solving - which card / piece / tile to use.
Let's get to it! Find a game, have FUN and learn!