There are almost 2,500 games at present that support Steam Trading Cards (and thus work with Idle Master). Here is a list:

http://psteamproxy.yuanyoumao.com/search/?snr=1_4_4__12&term=#sort_by=_ASC&category1=998&category2=29&page=1

Yep, looks like there's a bug in how this process is being carried out. I'll have it fixed up in the next release.

There is a separate Python (Linux) script you can run to accomplish this:

https://github.com/jshackles/idle_master_py/blob/master/Source/Idle%20Master%20Helper/idle-to-ready.py

You can run this first and then it will complete once all your card-eligible games have 2 hours of play time, then you can run the regular Idle Master script like normal.

This behavior should be fixed with version 1.3 that was just released. Try updating, and let me know if you continue having this issue.

Glimmer is correct and Jonno83900 is uninformed. With 252 games left to idle, Idle Master will attempt to idle each of those games simultaneously up to the 2 hour mark first (so that they're eligible for card drops) before idling games individually in sequence to earn trading cards.

Steam will only count playtime up to 30 games at a time, so this is the number Idle Master idles at once. This means you'll need to idle a total of 9 batches each for 2 hours before cards will start dropping - so you should expect to see your first card drop within 20 hours.

As Glimmer said, this is due to Steam's new refund policy requiring each game to be idled for 2 hours before it becomes eligible. In the Idle Master settings, you could set it to idle games individually - which in your case would initially be faster to start dropping cards but then each game has to be run for two hours before cards drop - meaning the entire process would take 252x2=504 hours + idling time to complete. So even though you have to initially wait 18 hours for all your games to be eligible, this will save you about 21 DAYS of idling time.

Hope this makes sense!

Is TF2 on your blacklist? There is also a bug I've identified where if you have a foil badge for a game that has card drops remaining, Idle Master may not recognize that game. Do you have the TF2 foil badge completed?

Steam will only recognize and record playtime for up to 30 games at once. Anything above that and the playtime isn't recorded in your profile. So it's current setting of 30 games is the most efficient way possible to idle multiple games at this time.

When Steam's servers are offline or unreachable, the current version of Idle Master will disconnect. Most likely what you're seeing is that Steam's servers were overloaded at some point while you're idling, and the program disconnects.

I'm working on a future update that will handle this situation a little better by retrying again after a certain amount of time has passed, rather than disconnecting completely. Steam's severs used to be rock solid and this wasn't really an issue. Lately their servers (especially in certain parts of the world) have been absolutely unreliable.

Do you have the latest version of Idle Master, including the latest version of steam-idle.exe?

A System.Net.WebExecption on System.Windows.Forms.PictureBox.Load() means that steam-idle.exe is trying to go out to the web to find the header image for that particular game and it's returning an exception (either the Steam store is down or that header image doesn't exist).

If you can figure out which game it is that's crashing IM (maybe by advancing "next" through them all in single-idle mode until it crashes again?) then you can add that game to your blacklist. Also if you find out what app it is let me know and I'll see if there's anything weird about it on the store.

Either way, the latest version of steam-idle.exe https://github.com/jshackles/idle_master/blob/master/Source/IdleMaster/Resources/steam-idle.exe?raw=true shouldn't throw this error.

Which version of Idle Master are you using? Versions older than 1.2 have this issue that was introduced by a change Steam made.