The first thing to check for, when you run a game, is that you don't see a big screen saying:
Remember, if you get that message, then it means that MAME doesn't emulate the game fully, and the problems you will have, when you try running it, will be the same for everyone else. The MAME developers may have problems completing the emulation, for one reason or another, and in the spirit of free source software, they will enable the game in a non-working state for others to work on and try to fix. If a game doesn't work yet, you can either wait for the next release of MAME, hoping it will be fixed, or you can try and fix it yourself. There are plenty of documents out there on how MAME works, and there's nothing stopping you from learning how to contribute to MAME.
THIS GAME DOESN'T WORK PROPERLY, TYPE 'OK' TO CONTINUE.
YES! As of MAME version 0.62 there is support for USB light guns. See http://www.act-labs.com/ for one such gun. This is not an endorsement of Act Lbas, other companies also make light guns that work with MAME.
NOTE: Many arcade games had "light" guns, that were in reality just mock up guns fixed to the top of a joystick and thus weren't really light gun games at all.
As of MAME 0.63 you can use the command line options "-skip_disclaimer" and "-skip_gameinfo" to remove the startup screens. You cannot however remove the incorrect emulation warnings.
For all previous versions of MAME you can't. Note that pressing "Left" then "Right" on the player one controller will remove this screen the same way that pressing "O" then "K" will.
You can try compiling MAME yourself after removing these screens. (See "Miscellaneous" Section)
There are two kinds of High-Score saving used in MAME, depending on whether the real arcade machine saved the High-Scores or not. Some arcade machines had some type or another of Non-Volatile RAM, that kept game settings and High-Scores when the arcade machine was turned off. This function of the original machine has also been emulated in MAME, and the contents of each arcade machines NVRAM is stored in the /nvram folder. Arcade machines without NV-RAM did not keep High-Scores when turned off. MAME only supports High Score saving for these machines, if they are included in the "hiscore.dat" file. The latest version of this file can be downloaded at http://www.mame.net/downmisc.html.
You may want to try MARP - the MAME Action Replay Page at http://marp.retrogames.com, with thousands of Game recordings available to view. Also, anyone can register and start submitting. See the page for more information.
First of all you should read the document files that come with MAME. It is amazing the number of people who ask questions, where the answer can be found so easily within the documents that are distributed with MAME.
If you still have problems or a query regarding MAME then check out the official MAME FAQ at http://www.mame.net/mamefaq.html if you *still* cannot find the answer, then you can post a message in alt.games.mame. Someone may have come across the problem before and be able to help. Members of the MAME team do visit here and you may be lucky enough to get an official reply. ;-)
In your mame directory there is a sub directory called "cfg". In "$MAMEDIR$/cfg" there is a file called "default.cfg", delete this file (With MAME not running). This will remove the default keymappings that MAME uses. If you have other files in "$MAMEDIR$/cfg" and they dont work after doing the above you need to delete these files too.
There are two likely reasons for this:
The new version of MAME says that I'm missing some ROMs , but this ROM-set *did* work in the earlier MAME!
Please remember, that if you download a new MAME, then there may occasionally be games that do not work. When something in the program is changed, this may lead to something else becoming broke. Always keep the last version of MAME you had, that ran the game okay and hope that it's fixed in the next release.
Pressing the "Tab"-key should bring up a menu, where you can select what keys to use for all games, and what keys to use for the current game. You can assign multiple keys / mouse-buttons for most actions.
Does your "Tab"-key not bring up the menu? See "Why won't TAB bring up the configure screen?" in section 5.
First you must remember that MAME is NOT MAME32 - it is still a command-line version of MAME, like Dos-MAME. What you need to do is:
MAME [gamename] [options if required]