All of the products tested in this review are in a constant state of development, and some of problems encountered by the reviewers may have been fixed. Consult the Math Engine and Havok Websites for the latest updates. You also know that creating a robust and flexible physical simulator is difficult work.
Simulators are hard to design, challenging to code, and even more difficult to debug.
These challenges cause many programmers and producers to look for external help for their physics development problems. We feel the market has matured to the point where it is time for us to take a hard look at these products to see how well they work. Our focus is on rigid body dynamics. We will not review cloth, particle, water, or other kinds of simulation, even though these packages support some of those features. First, it's important to point out that the stress tests are not exhaustive, nor directly representative of in-game situations.