This seems to have quite a lot of '46isms.

Fairly ordinary auction - the "waterfall" kind where when someone buys
the leftmost private anything else with one bid resolves. You buy them
in at 50-150% face value.

1 dimensional stock market, double and triple jumps, partial
capitalisation, go up at end of Stock Round if sold out, go down if
shares in Bank Pool, go down one step on player sales (only on
Director sales if the price is below 50 kroner (kr)). Companies that
close by hitting the bottom of the stock market can be refloated.

Public companies start as 5-share minors and can convert to 10-shares
through "nationalisation". Ordinarily only one company nationalises
per OR - or after the first OR only in Phase 2. From Phase 6 (when the
endgame is triggered) companies nationalise immediately. _Public_
companies have a unique power (as do some privates).

Mountain terrain keeps a "mountain token" unless you pay the terrain
cost a second time - either when first laying on the tile, or when
upgrading it (but not at any other time) to build a tunnel and remove
it. The effect of a mountain token is that for every train a company
runs to or through the hex, it pays 10 kr from its treasury - this
doesn't affect the train's run, and has to be paid in advance (no
half-paying to make the money to pay the charge. Warning: private
company P2A refers to this charge as "for snow on tracks"; elsewhere
in the rules it is "for maintenance"; those are the same game
mechanic.

You can buy ships, which are like trains but on the sea (this is not a
joke, they work pretty well like ordinary trains but on the blue bits
of the map). A ship does not satisfy the requirement to own a train.
Trains go obsolete (like 1846, running once before rusting); ships
don't.

The cert limit increases with the number of companies nationalised,
which since it affects the number of shares out there means I guess
the cert limit may matter earlier than the endgame. You can't own more
than 60% of a company. You can't sell in the first SR; you can't sell
a company that has not yet operated if you're not the Director. You
can't cause more than 50% of a company to be in the Bank Pool, or
cause a company to have no Director. You float at 60%.

You can issue and redeem shares just like in 1846.

Lay one or upgrade one; permissively (you only have to be able to
reach some of the track on the new tile with a train of any
length). The ship routes are preprinted; the bit in the rulebook about
"water hexes" is ordinary terrain costs like C28. I26 Mjosa upgrades
automatically to tiles LM1 at the start of Phase 3, and LM2 at the
start of Phase 5. You pay a ferry fee of 10 kr to run through it in
Phase 2, 5kr in Phases 3-4, and nothing thereafter.

As well as regular tokens you can place "port tokens" in coastal
cities. As far as I can see, a regular token does everything a port
token does; a port token just enables a ship to pass through a city.
However, you can place a port token if you can only reach the city by
sea (I think, with a ship you actually own, not one of infinite length
[1]) and port tokens are placed in a separate "harbour area" (which I
think can have any number of port tokens) so can be placed when the
city is full of ordinary tokens. A port token satisfies the requirement to
visit a friendly token for a ship's route, but not for a train.

Dits are bad, counting against a train's length.

You can half pay. You can double jump, or triple jump at 165kr and
above. Hitting the top of the stock market doesn't do you any good,
how sad.

You must own a train (and a ship doesn't count) even if you have no
route. Ships count against the train limit and additionally you cannot
have more than one ship of a given type. There are diseasel trains of
infinite length [1] with an upgrade discount for 4/5/6 trains like in
1830 and friends.

Bankruptcy does not end the game; if it produces a Directorless
company, that company withholds, drops two spaces if it has no trains
or ships at all, buys the cheapest train if it can.

In a nationalisation round, companies are offered the opportunity to
nationalise in reverse operating order (lowest price first). When a
Director accepts, the company becomes a 10-share; 4 shares go to the
treasury and one is immediately purchased by the "NSB" at face value.

When the first 6 is bought the game end is triggered; after the next
SR, there are three more ORs.

[1] yes Clare, very funny.