AM1 has been mismatched and changed time and time again.
In the very beginning they were known for the Beat em ups like Golden Axe and Dynamite Cop but most importantly House of the Dead. Movie-licenced shooters, some racing games (SEGA GT) were also part of the portfolio.
For a very quick time they were merged with the people that did RPG games and Shinobi.
But then they put into strict Arcade development. By far the biggest success was the card RTS game "Sangokushi Taisen" that went on and on for over 10 years now, and is still one of their biggest earners
In 2009, instead of the 3 teams, SEGA split the Arcade division, into 2. With 1 one being games mostly actual arcade games (AM2) with the other being card games, and other.
Well appearently the Arcade divisions do smartphone games too now; this is appearently the portfolio of AM1 now:
Chain Chronicles (I think this was by the RPG team leftovers then)
Various Medal games
The Sega Toylet game!
MaiMai
Puyo Puyo Arcade machine
Code of Joker
World of Three Kingdoms
Initial D games
http://buzz.sega.jp/