Q: What did the forced update for iPod touch 2g(A1288) achieve/do to my ipod?

See:

iPod touch: Which iOS 4 software features does my iPod touch support?

Asked and answered at the link below.

https://discussions.apple.com/message/18955780#18955780

The fact is that the App you want, CSR Racing, requires a 3rd generation Touch. That is stated in the Requirements for the App. So it will not run or install on your 2nd generation Touch, regardless of any updates that you eventually install.

The update (which was not "forced" at all) was probably designed to fix bugs and improve performance. That update came out some time ago (even though you have only just updated, as deduced from your other post)  and frankly, I for one, have forgotten exactly what it did.

Perhaps you should spend some time reading therough various posts in these discussions to understand the what, why and limitations of the update instead of posting a new question after Illaass has answered you in your other post.