New to S.trades

Everyone calculates the value of their goods differently
Overall, you can roughly calculate how you did it..... but it is and remains a matter of supply and demand

You can almost always assume that the games of cheap bundles like Indiegala, Fanatical, Groupees and all the other sites have almost no value and that nobody wants them either.....but once the price of a bundle exceeds 5-6 $€, things will look different again
Because fewer people will buy this bundle and will use most of the games

Humblebundle looks different again because the games are easy and save to resell or trade there than other bundle sites due to the Giftlink option and also because they usually have higher quality games

grab a tool like for example Enhanced Steam for your Webbrowser it will show you how often a game was bundled
(btw that a game was bundled for the first time or just a few times does not mean that it has any high value)
Or take a look here in the Forum under Deals there are mostly Charts for all Bundles
https://www.steamgifts.com/discussion/y1i6b/fanatical-all-stars-x-bundle

So how do you calculate the prices now? Can not be explained -> trial and error!! :P
Research in the Tradeforum for games you want to offer
Take your Chroma Squad for Example
I find over 300 open topics with people offering the game and even more closed topics
Here you should take what you get offered
Now look for Bounty Train and you'll see the difference

Has a game cards ? At least the number of trading cards it drops ...is its value ....preferably a little bit on top
otherwise it would be free for the buyer ....For less you would not have to wait for a buyer
there you could just make a 2nd Steam account and farm the cards yourself or give it to a friend who does not have it and ask for the dropped cards^^

For games from higher value Bundles for example Humble BTA or Tier 3 or humble monthly orientate yourself on the price of reseller sites like g2a or kinguin etc ...your copies would usually end up there anyway if anyone shows interest, it is usually a reseller

As you can see, I probably didnt even help you a bit :O
at least to help you Hotline Miami 2 for Bounty Train is a good deal right now
Would you already be an experienced trader ...then your experience would tell you
that Bounty Train is a Daedalic game which is a developer / publisher who offer his games continuously in bundles
What means Bounty Train will probably not immediately but to 100% in the future massively lose value

If you want a rough estimate, just look up how much the game costs on grey market sites. Calculate the average of the G2A and Kinguin price, and undercut it by 20-40%. A Chroma Squad key could probably be worth around 0.50€, but some may go as low as 0.30€.

Bounty train for hotline mami 2 seems like a fair trade to me comparing the prices of the two games on the grey market.

Usually i just use isthereanydeal.com and allkeyshop.com for references and current pricing, which should represent actual market value for keys.

what do you think about Hotline Miami 2: Wrong Number (not the Digital Special Edition) for Bounty Train?

It's a fair trade.