I'm trying to develop a TCG(trading card game) in Unity(I'm Unity newbie) and currently stuck on the architecture of the project and the card effects in particular. Coming from web development background for me all the logic and card effects should be on the server but going through some tutorials for Unity I think the logic should be on the client and I should use a simple room-based server to notify for player actions. Is that correct?
To summarize - where the game logic should be(e.g. card effects, rounds etc)? On the client or on the server?
I actually worked on one of the major TCG's out now for iOS/droid, so this is coming from experience. You definitely want all game logic and rules to be on the server. Do not trust your client to be the source of truth for any game outcomes etc. People will be able to hack that by tampering with the data sent back to the server. They don't have to decompile the game to do that, it can be done merely by sniffing the net traffic.
That said, you may end up with some duplicated logic on both client and server, only so that you can enforce game rules and display the outcomes without always hitting the server. However, your server is always the source of truth and the client is just there to accept input and display outcomes.
The general flow was the client would send a message requesting a new game to the server. The server would respond with the cards for each side and the opening move for the first player. Then the client would simply parse each move and display the outcome. On the cards objects we had methods for many of the actions, such as DrainHealth() and BuffAttack(). When called, these methods would trigger things like particle effects and sound fx attached to the card script.