I've looked at a number of implementations of the board game Hive, which uses a technically unbounded hexagonal layout. Most of them have read your article and really like the 3-axis cube system, usually with hash table representation. As the core of a minimax engine, this is very inefficient, so my engine uses a [wrapping 16x16 rhombus](https://github.com/edre/nokamute/blob/master/src/hex_grid.rs) in a packed 256-entry array. The adjacency operations are very fast, but I have yet to come up with a way to efficiently compute distance...