"What ifs" are on one hand a bit daft, but can be a fun thing and wargamers love them. Here is a good one - https://acoup.blog/2025/05/16/collections-alexander-goes-west-a-silly-counterfactual/
I'd add that the links in there to his series on the phalanx vs. legion are well worth a read if you have the inclination; very informative.