For maximum security, use maximum paranoia. Assume that any script or wallet he gives you is invasive malware that's intent on stealing your bitcoins.

Create a brand new wallet (on a different machine, that's never had his stuff installed) using the standard client and configuration (not anything that he set up for you), and send any remaining bitcoins from your old wallet to your new one.

Then delete both the bitcoind wallet and game script, and if in doubt, wipe the computer(s) that had them installed and only reinstall trusted things.

For a lower, but still reasonable, level of security/paranoia, create a new wallet with a new password and transfer the old wallet's bitcoins to it. It's important to not reuse a possibly-compromised wallet, even with a new password and new addresses, because of the key pool. This pool basically means that he's (possibly) already downloaded your private keys, not just for your past addresses, but for your next 100, too.

And if possible, inspect the game script for anything suspicious, or simply stop using it. Or use it only on a computer that cannot access the bitcoins, and in which you never type your wallet password.

In any case, do not use any passwords (RPC, wallet, etc.) or wallets that he gave you, since they could be compromised.