Do you have Steam installed natively or as a Flatpak?

Can you screenshot the error message?

If you have Steam installed natively try running it from the terminal by simply typing it's name and see if it spits out anything interesting when you launch a game.

I try to run the games from KDE games menu or 'recent programs' as in Kubuntu 19.10.
If I try from steams, I get no message, but the games don't start.

I'm sorry I don't know what Flatpack is...

Yes there may be some clues here
I am running on intel core i7 with nvidia mx150

GameAction [AppID 1066780, ActionID 2] : LaunchApp changed task to ProcessingInstallScript with ""
GameAction [AppID 1066780, ActionID 2] : LaunchApp changed task to SynchronizingCloud with ""
GameAction [AppID 1066780, ActionID 2] : LaunchApp changed task to SiteLicenseSeatCheckout with ""
GameAction [AppID 1066780, ActionID 2] : LaunchApp changed task to CreatingProcess with ""
GameAction [AppID 1066780, ActionID 2] : LaunchApp waiting for user response to CreatingProcess ""
GameAction [AppID 1066780, ActionID 2] : LaunchApp continues with user response "CreatingProcess"
Game update: AppID 1066780 "", ProcID 17893, IP 0.0.0.0:0
Starting app 1066780
>>> Adding process 17893 for game ID 1066780
ERROR: ld.so: object '/home/sg/.local/share/Steam/ubuntu12_32/gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS32): ignored.
GameAction [AppID 1066780, ActionID 2] : LaunchApp changed task to WaitingGameWindow with ""
ERROR: ld.so: object '/home/sg/.local/share/Steam/ubuntu12_32/gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS32): ignored.
GameAction [AppID 1066780, ActionID 2] : LaunchApp changed task to Completed with ""
>>> Adding process 17894 for game ID 1066780
ERROR: ld.so: object '/home/sg/.local/share/Steam/ubuntu12_32/gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS32): ignored.
>>> Adding process 17895 for game ID 1066780
>>> Adding process 17896 for game ID 1066780
[S_API] SteamAPI_Init(): Loaded '/home/sg/.local/share/Steam/linux64/steamclient.so' OK.
Game update: AppID 1066780 "", ProcID 17896, IP 0.0.0.0:0
RecordSteamInterfaceCreation (PID 17896): SteamUtils007 / Utils
RecordSteamInterfaceCreation (PID 17896): SteamUser017 / User
RecordSteamInterfaceCreation (PID 17896): STEAMAPPTICKET_INTERFACE_VERSION001 /
Game update: AppID 1066780 "", ProcID 17896, IP 0.0.0.0:0
RecordSteamInterfaceCreation (PID 17896): SteamUtils009 / Utils
Setting breakpad minidump AppID = 1066780
RecordSteamInterfaceCreation (PID 17896): SteamUser020 / User
Steam_SetMinidumpSteamID: Caching Steam ID: 76561198415445092 [API loaded no]
RecordSteamInterfaceCreation (PID 17896): STEAMUSERSTATS_INTERFACE_VERSION011 /
RecordSteamInterfaceCreation (PID 17896): STEAMAPPS_INTERFACE_VERSION008 /
RecordSteamInterfaceCreation (PID 17896): SteamFriends017 /
RecordSteamInterfaceCreation (PID 17896): SteamUser020 /
user data folder: /home/sg/.local/share/Steam/userdata/455179364/1066780/local/
libGL error: MESA-LOADER: failed to open iris (search paths /usr/lib/x86_64-linux-gnu/dri:\$${ORIGIN}/dri:/usr/lib/dri)
libGL error: failed to load driver: iris
libGL error: MESA-LOADER: failed to open iris (search paths /usr/lib/x86_64-linux-gnu/dri:\$${ORIGIN}/dri:/usr/lib/dri)
libGL error: failed to load driver: iris
libGL error: MESA-LOADER: failed to open swrast (search paths /usr/lib/x86_64-linux-gnu/dri:\$${ORIGIN}/dri:/usr/lib/dri)
libGL error: failed to load driver: swrast
X Error of failed request: GLXBadContext
Major opcode of failed request: 152 (GLX)
Minor opcode of failed request: 6 (X_GLXIsDirect)
Serial number of failed request: 113
Current serial number in output stream: 112
Game removed: AppID 1066780 "", ProcID 17896
Game 1066780 created interface STEAMAPPS_INTERFACE_VERSION008 /
Game 1066780 created interface STEAMAPPTICKET_INTERFACE_VERSION001 /
Game 1066780 created interface STEAMUSERSTATS_INTERFACE_VERSION011 /
Game 1066780 created interface SteamFriends017 /
Game 1066780 created interface SteamUser017 / User
Game 1066780 created interface SteamUser020 /
Game 1066780 created interface SteamUser020 / User
Game 1066780 created interface SteamUtils007 / Utils
Game 1066780 created interface SteamUtils009 / Utils
Game 1066780 method call count for IClientUser::GetAppOwnershipTicketExtendedData : 1
Game 1066780 method call count for IClientUser::GetUserDataFolder : 1
Game 1066780 method call count for IClientUser::GetSteamID : 3
Game 1066780 method call count for IClientFriends::GetPersonaName : 1
Game 1066780 method call count for IClientUtils::GetAppID : 11
Game 1066780 method call count for IClientUtils::GetConnectedUniverse : 1
Game 1066780 method call count for IClientUtils::RecordSteamInterfaceCreation : 9
Game 1066780 method call count for IClientAppManager::GetCurrentLanguage : 1
Game 1066780 method call count for IClientUserStats::RequestCurrentStats : 1
Uploaded AppInterfaceStats to Steam
Exiting app 1066780
No cached sticky mapping in ActivateActionSet.Steam: An X Error occurred
X Error of failed request: BadWindow (invalid Window parameter)
Major opcode of failed request: 40 (X_TranslateCoords)
Resource id in failed request: 0x2400327
Serial number of failed request: 14598
xerror_handler: X failed, continuing

Steam output looks fine, but since you are launching your games through another launcher its likely not a Steam issue.

You are probably best off asking on the Kubuntu forums, this seems like a bug.

https://www.kubuntuforums.net/forum.php

There are two issues.
1. Transport Fever 2 does no longer work when the graphics card is in "Nvidia on demand mode", or the mode does not work with ubuntu 20.4

2. The method that I used to start the game
steam steam://rungameid/1066780
does no longer work because the steam command is not found.

You need to install the appropriate 32 bit packages for your video driver.

How would I tell which packages that would be?

Re-installing Steam fixed the "Could not find the program 'steam'" problem.

Originally posted by stein:

There are two issues.
1. Transport Fever 2 does no longer work when the graphics card is in "Nvidia on demand mode", or the mode does not work with ubuntu 20.4

2. The method that I used to start the game
steam steam://rungameid/1066780
does no longer work because the steam command is not found.

if you look at the error report your posted (bottom half libGL errors) its trying to run off iris graphics driver mesa for your integrated graphics and NOT nvidia. Go to driver manager and install nvidia xxx.xx (recommended driver will be found automatically)

Sometimes a different distro or different version of a distro install the executable in another place. I fixed that error with a link to where it is installed. First I checked with "whereis steam" command.

sudo ln -s /usr/bin/steam /usr/games/steam

Originally posted by Tuxar:

Sometimes a different distro or different version of a distro install the executable in another place. I fixed that error with a link to where it is installed. First I checked with "whereis steam" command.

sudo ln -s /usr/bin/steam /usr/games/steam

nice bro, you save me