New Variant: Cylinder Chess

Congrats to your brother, he must been older than Methusalem. According to Wikipedia, Cylinder Chess is first mentioned A.D. 947 by the Arabic historian Ali al-Masudi (https://en.m.wikipedia.org/wiki/Cylinder_chess)

nb: that Wikipedia entry is incorrect. The book by al-Masudi does list six versions of chess, but this version of cylindrical chess is not among the six. 
This version of cylindrical chess is a relatively obvious variant, so has been "invented" several times. Other inventors include Don Green ("Noble Celts") and Raymond H. Loomis ("CHECKCHESS RoundBoard")

As for the book by al-Masudi, the six versions of chess mentioned were:

1. "ordinary" 8x8 chess
2. a version played on a 4x16 board
3. a version played on a 10x10 board with dabbaba, pieces that move like kings but are ordinary pieces otherwise
4. Byzantine chess (circular chess that is very distinct from cylindrical chess; it was well-known at the time and much more playable and interesting than the simple cylindrical variant)
5. Another version played on a circular board called zodiacal/astrological chess, with the board divided into 12 sections and played with pieces of 7 different colors.
6. A "modern" (in al-Masudi's time) version called organic played on a 7x8 board with six different pieces representing the six organs or members which correspond to sense, speech, hearing, sight, touch, and move and the "king" piece, the heart. 

Source: Meadows of Gold by Abu al-Hasan Ali ibn al-Husain ibn Ali ibn Abd Allah al-Mas'udi, translated by Paul Linde and Caroline Stone, Kegan Paul International, 1989, p. 395