the rules of snooker actually specifically exclude non-standard equipment by defining required specifications and tolerances. No special, non-standard equipment is defined, therefore, no special, non-standard rules are needed.
On the other hand, of course, non-standard equipment exists, and you are correct that while generally not directly proportional, if the table surface size changes, most of the other dimensions will also be changed to some degree. If the changes were actually directly proportional for all relevant dimensions, then game play on a 3 x 6 ft. Table would be on a surface 15 inches above the level ground, the balls would be about the size of ping pong balls, cue shafts would be the diameter of a drinking straw, the overall cue would be the length of your arm, and the game could only be played by leprechauns about 3 feet tall.
i can say that, ironically, while an american snooker table playing surface is about 5 x 10 ft., the "official" balls for american snooker are actually a larger diameter than standard snooker balls. So perhaps your hypothetical situation would be possible in that proportionally smaller "d". I don't know; i have no easy access to this type of equipment and i have no desire or inclination to do the required calculations.
So if we may venture from the sublime to the ridiculous....
Let us imagine that two players, for reasons of their own, decide to play an important match (exhibition? Wager?) on some non-standard table and are both stubborn and will not agree to nullify a frame by stalemate. They manage to find a very meek certified referee who will agree to oversee their match despite the fact the the rules of snooker section 1., rule number 1. (a) has already been broken before either of them plays a stroke and the referee has a shyness disorder so that he will not impose and enforce a stalemate nor an unsportsmanlike conduct warning upon them in any circumstance. Upon further review, i don't exactly agree with scaramouche's ruling on your hypothetical, so here is how i believe the frame would pan out...
Player a commits a foul with an in-off and in the process of the stroke, the entire area within the "d" is effectively covered as you suggest. Incoming player b gains four points (assuming no other, greater foul) and so has the usual options. Obviously, only a fool would accept this shot, so of course, he hands the following stroke back to player a who must attempt to place the cue ball, which is, of course, impossible. In the process of trying to place, of course, player a somehow, but not so surprisingly, disturbs other balls in play before a stroke can even be played. Foul, four more away (again assuming no other, greater point value foul), and player b will again have the usual options. But....you must also understand that there is a rule of snooker, section 5, rule 1. (a), (ii), which states, "the referee shall...be free to make a decision in the interests of fair play for any situation not covered adequately by these rules..."
in our hypothetical situation, the way that section 5., rule 1. (a) (ii) can and likely (well....not really "likely" i suppose) would be implemented would be by using long honored precedent that a player may not in some way benefit by the willful or accidental committing of a foul. So that our meek, but dutiful, referee must essentially treat the situation in the same way as a foul and a miss even though an actual stroke has not been played, not allowing player a to benefit by illegally moving the object balls in this way. Player b would of course call for the balls to be replaced. So (it may take some time, but) this circus act would be repeated time and time again until the 37th consecutive foul is committed resulting in a current frame score of 148 to zero. At that point in the frame, perhaps an hour or more later, snookers are now required therefore (assuming that the trying of the patience of player a has not by now led him to some blatant unsportsmanlike conduct that even our submissive referee cannot ignore) the balls will not be replaced to their original position and the frame can continue as normal.
May i then also submit in this unlikely scenario that player a in fact gains his required penalty points via snooker, then, from a deficit of 148 to 4, manages to compile the break of his life, with fifteen reds and fifteen blacks, then all colors through to pink, only to go in-off the black from spot. It is a brutal game.
