Finding your old unused keys...

It means you have the game. Finding out whether the key was or wasn't used is a matter of luck. Just throw them down and hope for the best!

It does not mean anything. There's no way of telling if a key is used or not apart from redeeming it in an account that does not have the game. That will consume the key in the process, however.

I put all keys I have in one text archive, and delete or mark red used ones, but if you didn't did this at begin, this won't help you knowing if it's used or not :S

you can give them on forum in case it did not work and you do not want to have not received in your account

Do this

1. creat a new account
2. Use the keys on that account
3. If enough games are added on the account that you dont wanna give the account away
4. ????
5. Profit
   (I did this before when i had like 100 keys laying in my inbox i gave away the steam account and have never taken it back :)

Though some logic and deductive reasoning I've managed to figure out with 99% certainty which ones are unused. Here goes :)

Only way I know to test a key is by trying to activate it on an account that doesn't own that game. If it works, you just burned up an unused key. :(

I keep a spreadsheet to track which keys I've activated.

In steam you can see the games you redeemed with a date. Compare the date with the date of the bundle.

https://store.steampowered.com/account/

Edit: Sorry no date, compare it with the activated games