When is a port of an arcade game not necessarily a port? When it was programmed before the arcade game, but then released afterward. That's just about the case here, where Road Runner for 2600 was started in 1984, then shelved for five years, after which it was dusted off, updated and released. There are enough differences between this version and the arcade game that one could argue the two titles should be considered indepedently of each other. However, it is also obvious the arcade game heavily influenced the 2600 version, especially when the final 2600 release is compared to a 1984 prototype. All in all, the 2600 game may not have been intended to be a direct port of the arcade game -- and indeed it is not credited as such -- but it's close enough to warrant a comparison. Really the differences aren't that dramatic after you take the level rearrangements into account. The arcade game's first level appears here more or less as every odd-numbered level, and then elements from the arcade game's second, third and fourth levels are combined in unique ways for this version's even-numbered levels.
Technicalities aside, 2600 Road Runner fares about the same whether it is being viewed on its own or in comparison to the arcade game. Unfortunately, the view is not very favorable. The game looks pretty good, and certainly gives the impression the 2600 is being pushed to its limits. However, it just isn't all that much fun. Incredibly high difficulty is part of the problem, but so is the game's lack of any sense of speed or urgency, essential to any game about the Road Runner. Some more tunes also would have been nice, even if it meant having the same background theme in every level.
The Atari 2600 has proven (and in fact continues to prove) it can do far more than its creators originally intended. Road Runner demonstrates that, but it also demonstrates you need more than clever programming to make a good game. You also need to make the game worth playing!
Grade: C+.