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Well, last time I went to the parks, it was me, my girlfriend, and sometimes a friend of hers. Our mainstays were Heads Up, a variant of Mastermind played with words and guessing letters rather than colors, trading turns on the app Lex.
There are some board games entirely played in 'the hand', too. Board games like oddball Aeronauts, Love Letter, and so on.
Me and my girlfriend also brought our 3DS systems, but we rarely used those. We often just talked, relaxed, or read ebooks. I got through a LOT of books that trip.