Is this a chess 960 starting position? which? can I play it on casual?

To cover some partial answers:

I could try the board editor, "from position", variant, and continue from here.

The king is between rooks, so my current understanding of the set of starting positions is respected.

However, does lichess "From position" variant in that tool include the castling logic of 960, is my practical question?
The starting position only consequent mobility rule extension from standard.

I can't play with my account as opponent can I? I guess I could ask a guinea pig user (should be a friend with time to spare and ready to indulge that kind of curiosity... I will ask my father).

The fixation on RANDOM I.C. combined with the supremacy of competitive tournament administration mentality has gone too far, preventing analytic chess minded users from using tools accessible on lichess.

Seems like a policy feature hole.
Like old windows flavors containing all versions but having locked features downward. A pure marketing limit, not a software limitation. Maybe that is obvious, and then back to first paragraph.

@dboing said in #1:
> lichess.org/editor/brnqknrb/pppppppp/8/8/8/8/PPPPPPPP/BRNQKNRB_w_-_-_0_1

looks like a valid starting position to me.

I will report here if "From position" casual game on lichess continuing from that FEN does indeed include 960 board logic.

The "From position" with that FEN continued as game, do not compute that this is a 960 initial position. No castling (with king on rook user manipulation) possible.

So, there we have it. the hole.

More news (not really, expected). The hole is very active. I tried using the lichess PGN import syntax in study for variants and apparently on surface the study features do accept that as 960 variant in its display, however the appropriate castling board feature is inactive.... I find this silly to be honest.

Anyone heard of casual games played without the sacro-saint rating as objective?

I made a public study without any annotation of comments called
Testing 960 board logic (lichess study boards that is).
lichess.org/study/DByVoleC
(dummy black replies to get to empty back ranks)
960 not implemented there, but offered as possibility upon study/chapter creation.

Unless momentary lapse, the 3 chapters should be legit (albeit not random) 960 initial positions.

The first chapter only has the B and N swapped, and keeps the castling logic of standard initial position.

But the 2 next chapters seem to show that 960 castling logic is absent, although I could create them using the study creation dialog which DOES have 960 in its variants drop down menu.

In 960 random initial position games (the few I have tried) sliding King on rook, when back rank conditions are satisfied (and other chess mobility rules as in standard), that would work. (end of procedure always like standard chess square coordinates for K and R).

Maybe my manual 960 creations are not really 960 legal initial positions?
(yes, not random, I chose them, but I meant otherwise).

If you select standard variant (the default) and check all the castling options (4), it seems to be treated as chess960

Also whatever you said in #3 is unintelligible

edit: i.e. the corresponding FEN code (with castling rights) is lichess.org/editor/brnqknrb/pppppppp/8/8/8/8/PPPPPPPP/BRNQKNRB_w_KQkq_-_0_1