Hearthpwn

Basic Strategy:

This is a typical mech deck:  Flood the board with minions and overwhelm your opponent with under-costed creatures.    Since this is of the warrior variety, you want to take advantage of your weapons to protect your creatures when you can't make a favorable trade.

Notable Cards:

Warbot:   This works pretty well in an aggro meta since it can give you good board control early and trades favorably with Leper Gnome, Clockwork Gnome and Abusive Sergeant.   It also can buff up with a taskmaster to trade up the curve and counts as a mech which is important for synergy with the rest of the deck.

Screwjank Clunker:  The signature card in mechwarrior, can buff your creatures considerably for great board control.   Ideal targets are Mechwarper and Annoy-o-Tron.

Gorillabot A-3:  I really like this card in this deck since it solves the lack of card craw in warrior nicely without resorting to things like Gnomish Inventor.   The mech's you can pull often give you a nice late game play.   

Edit:  This deck was really struggling above rank 10 with control decks so I made adjustments to have a better matchup against control.   I dropped Clockwork Gnome and Harvest Golem in favor of Fel Reaver and Sir Finley.   Sir Finley's battlecry is basically irrelevant or even a downgrade against aggro decks, but at least it's a 1/3 body.   Against control it can really swing the game if you switch over to the Hunter or Warlock HP so I think it's worth playing at this point.

Cards I'm not using:

Fel Reaver:   This could be swapped in but the deck is more interested in board control than constantly going face and I felt the reaver can hurt that strategy, especially against aggro decks.   If you see control decks constantly it's a consideration over Harvest Golem although Golem is still nice against board wipes.

Sir Finley Mrrgglton:  I initially tried him but since this deck is midrange you generally don't want to change up your hero power against aggro decks.  Against control he's better though so it's a meta choice not to use him.   If you face constant control decks he's probably better than Warbot.

Arcanite Reaper:   This isn't a face deck, it's a board control deck.   Reaper doesn't fit here.

Kor'kron Elite:  It might be considered over the gorillabot if you want to swap him in.     The 4 slot is glutted though so that's the only card I'd swap him in for and that hurts your matchups against control.

Substitutions:

Fel Reaver >> Clockwork Knight

Loatheb >> Siege Engine or Clockwork Knight

Dr. Boom >> Stormwind Champion

Grommash Hellscream >> Force-Tank MAX

Iron Juggernaut, Ragnaros the Firelord and Piloted Sky Golem are also considerations as substitutions for the above cards if you happen to have them.