This variant limits the pieces in the game to those in the box. In the original Nova Games Edition this was an official rule. Chips may be used during the initial setup, but they must be replaced by pieces as soon as possible. Only available pieces can be built, no building in anticipation of losses is allowed. Units can be removed to allow others to be built. For units shared between nations, I divided the available pieces by the number of players, rounding all fractions up).
This variant has a number of beneficial effects. A greater variety of units are built, as you can't just build hordes of infantry. Risky moves are more common as you can rebuild the lost units. The players must make hard choices on how to allocate limited manpower.
The numbers listed here can also be used by scenario designers, to get a sense of the proper force ratios.
These limits can be enforced through the MaxBuiltPerPlayer property.