This thread is mainly about games in the golden age, as, due to the graphics of the time and such, there were certain peculiarities.
This first category I'm mentioning more of what I felt as a kid when I encountered these games. While I generally still agree with the sentiments below, I've more or less accepted how the games are...although Tutankham I would hack to make it better.
Could be cooler:
Robotron - didn't like, because nothing happened. Plus, the sudden stop and the sound effect used was just disturbing.
Defender - killer explosion. Didn't like the delay-time precursor to it.
Zaxxon - ditto with Defender.
Gyruss - again, ditto with Defender. The game is top-notch, except for the small delay in the ship explosion. Maybe even half the delay time would be better.
Tutankham - killer death sign....then they blew it with the Defender-like explosion, except it itself blew chuncks because it was so blocky looking. Maybe they were worried about any parallel with Frogger?
Zoo Keeper - again the secondary explosion thing. Either one would've been fine, but pick one of 'em.
Cool deaths:
Congo Bongo - just totally great. I remember laughing at this one.
Centipede - brutal and just right period of disintegration.
Pac-Man, of course - he just wittle down ta nothin! This one kinda confused me as a kid.
Joust - you're just done.
Asteriods Deluxe - totally improving upon the original, the ship really flies apart.
Frogger - splat
I, Robot when the EYe gets ya - you're just ------ done.
Q-bert - sorta outside the box, but cool anyways. Everybody I knew thought the game was just wacko cos of the speech and speech balloons.
Honorable mentins outside the period:
Black Tiger - totally fantastic, and kinda weird cos isn't he just mortal?, but cool anyways.
Both GnG games - you are bones now!
Rastan - a little delayed, but kinda neat