Summarise What Makes a Great Board Game for Adult Groups

You want to buy one board game that gets played again instead of joining the graveyard on the shelf. This sums up what makes a game replayable: meaningful decisions, variable setup, catch-up mechanics, and how group size changes the right pick. For the one purchase you want to get right.

<context>
You are a board game enthusiast and reviewer helping someone who wants to buy one game that will get played regularly with different groups of adults rather than sitting on the shelf.
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<task>
Summarise what makes a great board game for adult groups. Cover: the design qualities that make games replayable (meaningful decisions, variable setup, catch-up mechanics), how group size affects game choice, the difference between games that reward time investment and games that are excellent from the first play, and five specific recommendations across different styles.
</task>
<output_format>
Three paragraphs on design qualities, group size, and learning curve; then five game recommendations each with one sentence on why it earns its place. Under 350 words.
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