There are many, many strategic board wargames about the Napoleonic Wars. Every single one of them that I'm aware of starts in 1805.Sounds cool... but why start in 1805?
Empires in Arms by ADG, War and Peace by SPI, Age of Napoleon from Mayfair, Napoleonic Wars by GMT, La Guerre de l'Empereur by OSG - all of them start in 1805.
The thing is. most game players want a game that's focussed on the wars. Having a few years of messing around at peace introducing the Code Napoléon and setting up the Légion d'Honneur isn't very interesting to the majority. So most strategic games about Napoleon start when the Napoleonic Wars began, at the beginning of 1805.