Barring the increasingly popular, play a 3rd prop at loose forward. Does anybody know of any random rugby league formations that have famously been used over the years, maybe utilising 3/4 half backs on the pitch at the same time? Playing one less prop or something?

I can't imagine there will be too many, but will be interesting to read of some whackt tactics

GB over the years: As many loose forwards as you could possibly squeeze onto the pitch, in pretty much any position (except loose forward)

Hide a halfback at fullback until half time, then the old switcheroo

Halfback at Fullback, Fullback at Halfback, Halfback at Hooker, Winger at 2nd row, 2nd row at prop

McNally, Grix, Robinson, Lawrence, Fa'alogo against Crusaders last sunday.

We don't really get this happen, as we're more about roles and tactics than formations. A player might get asked to take on a different role, i.e. a winger asked to line up at prop and take a few drives up, but it's not really a change of formation.

The major changes there lately have been:
Halves playing left and right rather than 1st and 2nd receiver.
The interchange hooker
The ball playing fullback, as an extra halfback, replacing:
The ball playing loose forward, who is now frequently a middle of the pitch runner, an extra prop.

One unusual thing I have seen is that Leeds, under Darryl Powell, once played with two hookers playing left side and right side, on the field at the same time.

Seen 5 props and a hooker as a starting pack before.

Didn't Sydney Roosters employ just 1 marker for a while at the beginning of a season a couple of years back (until they got banjoed in every game and changed back). That is probably a tactic and not a formation anyway.

Here's one for you I don't recall seeing for a while. But it's an alternative defensive line-up as opposed to an attacking one. When was the last time you saw somebody play with a sweeper i.e. a defender sweeping up between the main defensive line and the fullback. I think Halifax used this to some effect when they won the title under Chris Anderson and other teams certainly used it at the time (1980s).

Leeds playing without a hooker when Matt Diskin was injured in 2007 and naming an extra prop (Ian Kirke amongst others) in his place. We ended up with Burrow and Sinfield filling in at acting half.

Teams used to use the sweeper when the short chip kick in the middle of the field was in vogue. Even without a sweper the chip is a high-risk play (more often than not turning over possession), which is probably why you don't see it very often.

It was rlthis gamerl and Lee Smith from full back took most of the dummy half role.

Forgot who it was, but on each side wing/centre/second row were virtually interchangeable.

We have an extra forward on the field with Joel Tomkins at centre and also an extra half back at full back with Sam Tomkins.

Apologies but this example is from wendyball. Way back I think in the 50's somebody renumbered all the all their players in a set of random numbers. This was when every team followed the same 1 to 11 convention where the right back (2) marked the left winger (11). Apparently is caused total confusion because the opposing team were searching for their usual man to mark. Again back in the 50's the Hungarians played in a different way with a Centre Forward who dropped into the hole rather than lead the line in a standard formation. Billy Wright was the Engalnd Centre Half and ended up following all over the pitch getting pulled completely out of position.

Third prop at hooker, and hooker replacing loose forward. This way, when the scrum is fed, it's like a big play-the-ball. Hooker can just dummy-half pass from the back of the scrum as standard.