SUMMARY The 4th row autofills from the talon when a column is empty. The rules state this shouldn't happen: "The fourth row is both your waste pile and playing pile. On an empty slot you can put any card from the first three rows, or one from the top of the fourth row." Autofilling from Talon dramatically limits available moves. STEPS TO REPRODUCE 1. Play Mod3 until a column on the 4th row is empty. 2. This happens regardless of the Autofill setting state. OBSERVED RESULT The game will automatically draw a card from the talon and fill the empty column. EXPECTED RESULT The column should remain empty until a player moves a card onto it or deals from the talon. ADDITIONAL INFORMATION I've only played Mod3 via Kpat, so I'm not entirely sure if it's the rule text or game logic that are in error. The current game logic dramatically limits potential ways to open spots in the first 3 rows though, so it feels incorrect to me.
I have not seen Mod3 anywhere else either, but I think the behaviour is normal because (IIRC) it occurs in both the dealer and solver parts of the code and so was intended by the original author. If anything, the documentation should be updated to included this rule. Personally, I play Mod3 quite a bit and I like this rule. It makes the whole game more challenging and therefore more interesting. It also gives Mod3 an "end game" that is quite different from the main game and you need to plan ahead for that , i.e. avoid building up deep piles in the tableau, ensure that "blocking" cards are removed from the foundation rows (such as a 5 in the top row with no 2 beneath it), and have at least one tableau column empty or ready to go out when the last tableau card is dealt.