From a David Crane interview:
I designed Outlaw and Howitzer. I don’t know…did it ever get out? I think it did. See, I did Outlaw for the 2600 at Atari. Outlaw, Slot Machine and Canyon
Bomber/Depth Charge were the three games I did at Atari before we moved on. But I was still at Atari for a year after doing that last 2600 game, because I was on the team doing the operating system for the 800. Then at the same time, I did a game that I always wanted to do on the 2600 but couldn’t because I didn’t have a writable playfield. That’s the game called Howitzer, where you basically sat on either side of a river and lobbed shells at one other, and wherever you left a crater, the other guy couldn’t drive over it. So you’ve got a strategy game of trying to modify his playfield while also trying to hit him, while avoiding his shots and following the trajectories to try to figure out where you’re going to get hit.
This is catalog number APX 10004