When I think mono-green, I think creatures, ramp, and pump. Magic 2010 provides it all in a strong, consistent package.
In the common slot, it gets Llanowar Elves, Rampant Growth, Elvish Visionary, and Borderland Ranger. Turn 1 Llanowar Elves remains a very powerful play in this format. Given both Rampant Growth and Borderland Ranger, it seems to make sense to go two colors to get more options. However, the uncommon slot provides two incredible options that reward sticking with just Forests in the deck.
The first is the deck’s namesake, Overrun. With GGG in its casting cost, sticking with just Forests ensures there’s never an issue casting it. It turns all of the small value creatures into lethal threats. The second uncommon is Howl of the Night Pack. Creating a 2/2 for each Forest you control, Howl provides an extremely powerful late game if the deck is forced deep.
Filling out the deck are the last uncommon, Cudgel Troll, and the two Rare/Mythics, Ant Queen and Garruk Wildspeaker. Ant Queen provides more late game options, while Garruk is a 3rd Overrun with some extra utility.
The sideboard brings mainly specific targeted answers. Naturalize and Acidic Slime come in for decks relying on artifacts or enchantments. Master of the Wild Hunt can provide targeted removal against other aggro decks. Windstorm to take down fliers. And Wurm’s Tooth for certain matchups where gaining a few life can flip the race.
Strengths: Consistent, flexible, powerful options both early and late
Weaknesses: Little interaction, can struggle against aggro sometimes