*Spectator mode - ability to spectate a player ingame. (useful for cheating prevention)
*Demo recorder - ability to record a player or themselves ingame. (This can be server-side or client-side your choice for what's best)
*Kick-Player / Kick-Ban Player - ability to kick players or ban players. (This can be ingame feature or Third-Party tool)
*Standard Server Admin abilities - change map, game-mode etc.
*Mod Tools - This is needed for competitive gaming.
*Dedicated Server Files - Needed for us to host servers.
*Server Browser - favourite server etc.