If you have played "Castlevania: SOTN," then you've already played this release.
"Castlevania: Circle of the Moon" for the GBA introduced an interesting twist when compared to previous Castlevania games. While it stayed true to its side-scrolling roots, "Castlevania: Circle of the Moon" utilized a tarot card system wherein the player would obtain tarot cards at different points in the game, and by combining two cards would unlock various talents and capabilities, such as increased strength (i.e. fewer strikes were required to dispatch an enemy), or the ability to hurl fireballs or other projectiles.
Konami is quickly running out of new ideas for its Castlevania franchise. They replayed the same theme through all the NES and SNES Castlevania titles before striking gold with "Castlevania: Symphony of the Night" on the PS1.
Since that point, Konami has been developing its Castlevania titles to mimic "Castlevania: Symphony of the Night," and "Castlevania: Circle of the Moon" is no exception. The tarot card gimmick was unique, but I believe Konami should seriously consider putting this series to bed, before the Castlevania franchise is ruined through sheer repetitiveness.