I'd make two suggestions:
1. Make players play all games - that way, if somebody is brilliant at a game, the tournament won't (hopefully) be one-sided this way. Make the selection of games fairly broad - Pac-Man, Galaga, Burgertime, Super Sprint, Street Fighter II and Ghosts 'n' Goblins, for instance.
2. Assign points for each game. Rather than just a fixed scale, assign them according to how close players are to the winner - ie - winner gets 100 points, and everybody else gets a percentage of 100, depending on how close they are. Winner scores 100,000, second scores 95,000 - 100 v. 95 points.
Sure, you need to do a few sums, but after a few drinks nobody will notice (or care...). This way, there's no outright winners on each game, and unless somebody score well ahead of everybody else, then the comp is open to the end.
Anyway, getting further isn't necessarily a better game, as somebody who hangs around to kill every enemy will score better, but may not get as far.
I arranged an 'Arcade Tournament' a few years ago as a fun event at our office., and followed basically the same approach as above (or basically as what Twin Galaxies does).
We selected 10 games, (a game released in each year from 1978 to 1987). IIRC the games were:
1978 - Space Invaders
1979 - Asteroids
1980 - Rally-X
1981 - Donkey Kong
1982 - Ms Pacman (technically 1981, but we had a 1982 bootleg PCB called Pac-Gal)
1983 - Gyruss
1984 - Kung Fu Master
1985 - Ghosts 'n Goblins
1986 - Wonder Boy
1987 - Double Dragon
Each player could practise as much as they wanted prior to the competition, however, on the day, they could play each game a maximum of 3 times (or less if preferred). The best of the 3 was then taken into account.
Regarding the scoring, we followed Twin Galaxies approach (as quoted by captainpotato), where the best score gets 100%, and each score is a percentage of that (Eg: if the best score was 15,000 pts that player got 100% for that game. If , another player got 13,200 points, they got 88% for that game).
Therefore, by the end of the evening, it was theoretically possible to get a maximum of 1,000 points (getting the best score in every game). The winner is simply the person with the most number of points.
Another important point is regarding the settings. We used the Twin Galaxies Tournament settings for all games.
A couple of things that I learned from this:
(01) 10 games is WAAAYYY too much. We started at midday on a saturday, with about 12 competitors, and only ended at around 03h00 sunday morning. If I was to do this again, I would use less games (perhaps 5 or so), or maybe not allow each player to play each game 3 times, but only a single time at the competition.
(02) There are a few games (like Wonder Boy), which are too easy to learn. Therefore for those that are 'rookies' at the game, they only play for about 3-5 minutes, but those that know the game a bit better, can keep playing for 30-45 minutes easily. Not only does this add to the problem raised in (01) above, but it also skews the points significantly, causing a massive points spread. (In our case, 2 guys got 100% and 93% respectively, whereas the other 10 players had less than 8%. Therefore, select games that are fairly challenging to all players, where you don't get to a 'watershed' point where you are so good at the game, you can continue forever.
(03) Regardless of whether you are using original arcade PCB's or MAME machines , make sure you have as many machines as possible, so that people can play in parallel. However, for fairness, ensure that all players play the same game on the same machine.
Regards
Olaf