Apologies if this has been discussed elsewhere and I know that we usually only talk about hardcore wargames here ( ??? ) but I stumbled upon an early access game when looking for something that my son would enjoy:
http://store.steampowered.com/app/346010/
The game reminds me of the web based "Fantastic Contraption" game but with siege weapons. Very addicting and challenging (and cheap). Thought some of you might enjoy this one.
http://grogheads.com/forums/index.php?topic=12537.msg327315;topicseen#msg327315 (http://grogheads.com/forums/index.php?topic=12537.msg327315;topicseen#msg327315)
You misspelled 'Beseige' (sic) in your original post so it didn't show up when I searched for it. ;)
Fun game, we spent a good deal of time with it the past couple of days.