I measured my Stratagame pieces and here are the results. The ship is 4.5 cm long, which is about the same size as an A&A American destroyer (the Stratagame ship being about 2 mm shorter and 2 mm wider). The infantry piece is 2.4 cm high. The artillery piece is 1.5 cm high. The mechanized infantry piece (a somewhat fanciful-looking APC) is 2.7 cm long. The light tank is 2.2 cm long and the heavy tank is 2.5 cm long, not counting the gun in either case.
The pieces are made of hard plastic, which I generally prefer over soft plastic, but I find their overall design to be disappointing. The pieces are more stylized than the A&A ones, with much less detail. The head of the infantry piece for example is basically just a cylinder with a helmet on top, with only the faintest possible suggestion of a nose and eyes. The ship looks reasonably okay from a distance, but from close up it’s a bit simplistic. In terms of detail and realism the best sculpt is probably the artillery piece.
At the time when Stratagame came out, the company which produced it had plans to publish a similar game set in ancient China, using Chinese junks and so forth as pieces. Nothing seems to have come of those plans, and Stratagame itself doesn’t seem to be published anymore.
I also checked out my Supremacy tanks, which are 2.8 cm long (3.2 cm with the gun), 1.5 cm wide and 1 cm high. As Holden said, they’re a bit on the large size compared to A&A tanks but they look great.