Taking my own challenge, let’s talk about one of the great classics: Contra from the NES. Nerds who know exactly what you mean if you talk about the spread gun, and many of us know the Konami code as the Contra code.
On the plus side, this was one of the great early mass slaughter games. If you wanted to pick up a machine gun and blow up some aliens, in the days before shotguns and zombies were all the rage, this was it. You had a variety of guns, cooperative multiplayer, and several variations on places in which to shoot them. When I was much younger, this was awesome.
On the down side, it was Nintendo hard. One-hit death with full item loss, three lives, and enemies with guns in multiple directions. Mix in flame jets, death pits, and spiked walls that spring from the ground. I blame development for arcades: “kill him frequently to take his quarters” does not port well to a non-quarter-based environment, to say nothing of the many games without saves, passwords, etc. (See also: online games that give you incentives to stay logged in AFK.)
Lessons to take away: (1) fake difficulty is bad. Elite monsters are not any more interesting than normal ones; they just have bigger numbers. Granted, the normal ones are not very interesting in group play, but it does not make something more interesting to give it 10x the hit points or damage. In Contra’s case, dodging a few shots is interesting, but dodging shots while on a moving cart beneath a splat-pillar maze, only to have a spiked wall pop up as you are almost to the last pillar, is bad. (2) Let’s make that a general case: it should be at least theoretically possible to beat the game on the first try, without random choices that sometimes lead to suicide, undisclosed boss fight mechanics, and all the other fun reasons why we follow online guides instead of just playing the game. (3) Understand your audience and platform. Do not design for the console as if it were a PC or an arcade stand-up. (4) Shooting things with your friends is fun. Preferably imaginary things rather than the neighbor children.
Bonus: speed run