A few years ago dynamic difficulty adjustment for videogames became a hot topic, first in the research world and then in game design too, thanks to titles like Left 4 Dead. Design novelty and technical innovation, right?

As usual, not really.

Here's the abstract of a patent filed 31 years ago by legendary toy maker Marvin Glass & Associates, for an Adaptive microcomputer controlled game.

Adaptive microcomputer controlled game

United States Patent 4,285,517

Inventors: Morrison; Howard J. (Deerfield, IL).
Assignee: Marvin Glass & Associates (Chicago, IL).
Appl. No.: 010,938
Filed: Feb. 9, 1979

Abstract

An adaptive game utilizes a microprocessor for generating a random audible or visual stimulus which must be responded to by a plurality of players. The response generally requires the players to estimate atime interval, a number of events, a tone frequency or the like. The microprocessor then correlates play with one or more players by determining the appropriateness of a player's response, assigning a score to the response and keeping score. In addition, the microprocessor senses the level of skill of the players by observing the score of the highest scoring player and adjusting the level of difficulty in accordance with the value of the highest score.