Inspired by Gregs suggestions for 10x10, I think I found an ideal setup for the next step from Chess to Chu Shogi. I call it Chu Chess. I did not want to use the RN compound, as it does not occur in Chu Shogi. Of the pieces that do, it seems Dragon Horse and Dragon King (Crowned Bishop and Crowned Rook) are the most suitable. They are just a small variation on Rook and Bishop, and as their pictograms also look similar to those, Chess players should not have much trouble handling them. The Crowned Bishop is similar in value to Rook, and the Crowned Rook an in-between for Rook and Queen. That strengthens the heavy end of the spectrum, to make life more difficult for the Lion. And it does provide better trading possibilities for the Lion than in Mighty-Lion Chess, namely L for Q + DK or DK + R + R, so that you are not stuck with it as much, and one Lion versus other material will be more common without the game being immediately decided. (Three-for-one trades are not as difficult with Lion as in ordinary Chess, as a Lion can capture two pieces, and could then be traded for a third.) Yet they don't disturb the ratio of Queen-class pieces to Rook-class pieces very much, if you count the Crowned Rook (to be called 'Crook?') as a bit of both.

The addition of those would make the piece spectrum a bit top-heavy, though. So I also wanted to add some Knight-class pieces. From the Chu pieces Gold would be a logical choice, but it is a bit frightening to Chess players because of its asymmetry. So instead I picked the Commoner, symbolizing the unification of all Generals and other steppers that are so abundant in Chu Shogi. It has a move familiar to Chess players.

I don't want it to be over-crowded, as Chu Shogi definitely is, so I don't want two full rows of pieces behind the Pawns. Yet 10x8 is too small to accomodate all the pieces I want. So 10x10 with a Grand-Chess-like sparsely-populated back rank seems an obvious choice. I don't want to disband castling, though, in my opinion that is a flaw in Grand Chess, where you have to march the King to a safe place in many steps, like in 'ranging Rook' games of (regular) Shogi. So I put the King on the back rank, ready to castle, making room for the Lion to stand shoulder to shoulder with the Queen in Chu-like fashion.

With castling the need for easy opening of the Rook files seems not so great, and the a-/j-file vacancies would even become a severe weakness after castling. They can be nicely filled with the Commoners. An extra Commoner as defender to make the King fortress more Lion-proof definitely would not be a luxory. On the side where you did not castle, the Commoner can be developed by playing up the Knight Pawn, and moving it out diagonally towards the center, putting the Bishop behind it afterwards. Unlike Knights, Commoners are 'Lion proof' when protected: the Lion cannot step next to them for an igui attack. The Rooks in the mean time are free to roam the back rank.

I thought about allowing promotion of some pieces, but that seems a little bit too un-Chess-like. I also thought about allowing the Pawn to promote to Commoner only, (In Shogi they promote to Gold, after all), but I am afraid this would make the end-game to radically different and drawish (when the first to promote has no way to stop opponent passers from also promoting, even if they still need 3 or 4 moves to do it). Extend the depth of the promotion zone to 3 ranks (including the initial Pawn rank, as in Chu) does seem a good idea, thoug, and again is reminiscent of Grand Chess.