This is a great simple game don't complicate it with too many unit types. I have all four games and the best for me is still Waterloo. Played loads and still can't win last Prussian battle on hardest level.
I think what would make a fun game, is making a totally separate app and combining all of your current pixel soldier games into one. But make only sandbox, so for example, seeing a bunch of red coats running up the beach of Normandy against a bunch of MG 08.
Many thanks to everyone who contributed! Here is the final tally for this poll…
Renaissance / Pike & Shotte (approx 1500 to 1700): 6
18th Century (1700 to 1792): 6
Napoleonic (1792 to 1815): 10
19th Century European and American Wars: 4
Colonial Wars (Examples: Zulu War, American West): 9
Early 20th Century (up to 1939): 4
World War 2: 13
Modern (1945 onward): 7
World War II wins, with Napoleonic warfare close behind. I was surprised to see that colonial warfare fared so well, coming in third place. Interestingly all the choices had at least a few votes. I may hold another poll in the future to see if the results change as more games get released.