Edited after figuring out answer:
This game, Rain of Terror, is a PAL ATR game for atari 8-bit. In MAME, it works sort of with the keyboard set up (only all left, all right or straight up), but it is supposed to be used with paddles to shoot at ~9 positions of a semi-circle from ground. I am using a 2600-daptor II to plug an atari 2600 paddle pair into the PC for MAME. Couldn't figure out how fire properly but figured it out later in post below. BTW, this is a contest winner from Europe.
Also, can anyone explain why there are five fields for the "paddle analog", "paddle analog dec" and "paddle analog inc" in MAME? Paddle only seems to move when I use the fifth "paddle analog" field.