Game Recording & Replays
Players should be able to save and record games they played. Also players be able to post them and share with other players.
The main thing about TCGONE is testing decks. To improve testing i consider that having a replay option from the last game we would be able to see the pros and cons from our build and work from that.
There are programs like that that can already do this like the screen-cast-o-matic for up to 15 minutes for the free version.
This would allow spectators to record games and be able to watch them in their own time. Can be expanded upon by implementing features such as the ability to pause or skip/choose turns.
You'll no longer have to worry about missing a single turn in the epic battle you're watching!