Reflexive shows everyone that match-3 games are alive and well with Big Kahuna Reef. They introduced a great refill mechanic--filling the board after a match is almost mesmerizing to watch.
Sprout Games releases Pizza Frenzy, which is a fun game about delivering pizzas to various customers. This was their last game before being bought out by PopCap Games. PopCap is, of course, most well-known for their Bejeweled series of games like Bejeweled 2 Deluxe.
This month puzzle games and action games were very popular:
Games Released in April 2005: