IMO the game relies too much on the mechanic of having to continually refuel your jet. How small is the plane's gas tank? Did it get punctured by enemy fire and is constantly leaking? I love the general layout and play mechanics otherwise, although it would have been cool to have the opportunity to fly over land to take out select high-value targets, etc., even if it had been made a significantly more difficult risk to do so, with tight paths through trees or somesuch. Another possibility would have been a base/boss at the end of every level, as seen in arcade Zaxxon, but the 2600 didn't exactly provide unlimited resources to the programmer, so it's somewhat understandable.