I’m a fan of the category of games categorized as “Abstract Strategy,” games with perfect information, typically not built on any kind of a theme, ones where you have to ponder constantly what to do next.
One of my favorites is Entropy designed in 1977 by Eric Soloman (rules).
Surprisingly difficult to find a copy but easy to make if you can assemble 49 tiles divided into seven different colors and a 7 x 7 board to put them on. Actually, those items are not particularly easy to find. For the longest time I used colored glass beads from the craft store and a paper printed grid. I found tiles at a thrift store that fit perfectly on a board for the game “Isolate,” (a somewhat mediocre game.)
A typical game:
Scoring is by done by finding vertical and horizontal palindromes, sets of colors that are the same both directions, from two tiles to seven. For example, the three yellow tiles in a row on the upper right hand corner score 7 points (2+2+3), the alternating green, purple green blue etc row across the middle scores 21. This particular game scored 112 points.
Nobody seemed to notice "Entropy" was misspelled in the song title! Fixed!