Vehicle mode
Fist off, here's a reference image for you via some concept art from the game.
Angled top view. The entire figure was given a wash of various browns and rust areas were drybrushed on with a dark brown/orange mix. I also did a light brown wash in the treads to simulate dirt that has collected.
Front view.
Right side view. Right side view. Here, I painted in the gears in the sides of his treads (copper and silver).
Back view. Simple detailing. Here you can see the two purple "lights" added to the back of the cannon.
Left view. Same details as the right side.
Underbelly. Basically just dirt and scratches created by drybrushing as well as some collected dirt/mud created with a wash of brown.
Top view. The dark grey triangular markings on either side of the cannon were previously red, but after looking at some reference images from the game, I decided to change them to grey for a more accurate appearance. I also added the Decepticon decal on the left side.
Robot mode
Again, a reference image for you via concept art from the game.
Front view. The figure's entire body was given an overhaul of drybrushing and other paint effects to simulate the large amount of wear and tear. His right lower arm was repainted light grey to better match the in-game look of the character. I also added some bullet holes/ damage to the upper arms with an exacto knife. While spraying the figure with Krylon matte finish to seal the paint, I accidentally smeared the Decepticon symbol on his chest, so I just painted over that area and later added a new one with a decal from Reprolabels.com.
I also painted all purple sections with glow in the dark paint from Coolglow.com. It appears clear in daylight, but glows purple in darkness.
Right side view.
Glowing right side view.
Back view. More detailing can be seen here. I added all the purple on his back, as the original figure had no painted details here at all, what-so-ever.
Glowing back view.
Left side view.
Glowing left side view.
Action pose.
360˚ view.
Glowing 360˚ view.