A500 and games (not working)

[orange]

have you tested the diskettes with x-copy?

[orange]

so, its not A500+ ? I'd try it without the ROM switcher, using only KS1.3 chip.
is additional 512Kb set as FAST, not CHIP ram?
I remember having problems with K3.1 in A500, due to missing some resistor set on board.

you can test RAM with some utility from aminet.

[orange]

if the board was modified to see expansion as CHIP RAM, it would do it for both cards. and some games need 512 FAST RAM. you can see type of RAM with command: avail

srecno..

[orange]

iirc, the games you listed as working require only 512K RAM (not sure about Another World though). I'd try more of 1Mb RAM games.
The 'usual procedure' is to re-seat all chips (or at least press down until you hear crack) and maybe replace capacitors, test voltages too.
There was also an "Advanced Amiga Analyzer", some of its tests can be used without extra hardware, perhaps it can help.

[orange]

A bit lost here ... the avail command stated that I have 512kb chip and 512kb fast ram. You think there's something wrong with my ram ? Which one ? The one on the MB, or the one on the expansion card(s) ?

could be, have you tried problematic games without the expansion RAM?

[orange]

it is strange.. I'd run WhichAmiga in it and WinUAE, to make sure its the same config.

[orange]

"This is not an executable file" message is normal. IIRC, you need to set file attributes to make it 'executable'. it can be done with directory opus or similar, and in AmigaDOS.

(some) file attributes and comments are lost when copying from PC because of different filesystem. so its best to copy .lha archives, because it preserves them.

but, I don't have idea what is causing games to not work. I would try to expand it with hdd and fast RAM in hope that 'whdload games' would work.

[orange]

@lauri
its possible. still, most games are NDOS and virus can only damage bootblock in such case. but then intro wouldn't load at all.

[orange]

viruses usually alter only executable files, not disk images or archives, I think.
(one could use .dms instead of .adf, to rule out data corruption in transfer, dms has some integrity check)