The retail Pentium version for some reason has a difference in the mech2.exe therefore it is incompatible with slugs patch.
However, if you have the pentium version that was not retail and was part of a bundle that version is generally compatible.
I would like to say that all of the non retail versions will work, but there are far too many different bundles for me to make that statement.
Now that I have said that, the simple answer is the following:
1. Download slugs patch here, and apply it to your mech2 directory.
2. After you have done that then you must set the compatibility mode of the mech2.exe. So in order to do that you need to browse to the directory where mech2 is located which is usually c:\Mech2\ or C:\Program Files\Activision\Mech2\ and then right click the mech2.exe and hit properties. Now that you are In the properties you will see a compatibility mode setting. You need to set the compatibility mode to Windows 98 or 95 it really does not make a difference which of the two you choose they work the same.
After you have done that, you are done, and are free to enjoy mech2!
Alternatively you could use the new wrapper, it does work, but it does have a bug in mechlab... you will only be able to use stock.
It can be fixed however if you combine the patch above (Extract it with 7-zip or another tool instead of installing) with this and use /-mechlab /-startup switches with the shortcut. Since the original patch does not have very many bugs, the advantage to doing this on top of the patch is that the player is capable of taking advantage of jumpjet and heat fix in the new wrapper.
