DEFCON
On Steam, it has CD key rotation feature once a month (old CD key is revoked and a new one is issued). Non-Steam players have permanent CD keys. While not affecting the gameplay in any way, it gives a player the following advantages:
- If a ban had been set on a CD key (authentication key ID) on DedCon server (
http://dedcon.simamo.de/), it can be evaded a month or less later. For non-Steam users, it will be permanent. The docs for DedCon mention this.
- If a CD key had been leaked, it will be eventually reissued for Steam users. Non-Steam users will have to put up with this (duplicate key users are kicked from servers, be them players or spectators), as Introversion Software hardly responds to emails anymore.