For the final word in your epic-scale games, try the OvercompensationHammer superheavy tank. Mounting a 8,000-calibre Mk. VI "Your Day Is About To Suck" Cannon, this baby will bring the pain to your enemies!
Fun fact: This model would actually be able to hold a real .50 BMG slug in its gun tube! Seriously! But please don't, because I don't want to be held accountable for the outcome.