Are there any ways better than peer review to validate a security
proof?
Peer review is and will always be (in my opinion) some of the best methods to verify a claim in general. However formal verification has started to gain ground on critical components, see for example in critical code components used in the software used in airplanes. However I doubt this trend has landed in the math field, not to mention crypto field.
Are there any ways to make your security proof easier to validate;
using a simulator based proof instead of a game based proof?
I didn't understand exactly the question.
Can we "reduce" a security proof to something validate-able in code?
There is this framework called certicrypt which was first published here and you can find their code here. It is written in Coq, so the proof itself has to be written in Coq. It has been is used to verify game based proofs, for example ElGamal, HashedElGamal, OAEP, FDH, and some ZKP protocols. A lot of examples can be found here.