of four is shot afterwards, a flashing UFO will appear. Shooting that accesses the Bonus Round, in which a player is given a short time to complete a certain goal, such as defeating so many aliens. If the task is completed, the game enters 'Fever Time', awarding the player with an even more powerful up for a short time, allowing the player to get through waves of enemies faster. Getting different combinations of colors can reap different bonuses, such as a roulette UFO that offers bonuses such as Freeze and Extra Player, changing all the aliens to the same color, or turning all enemies turn into UFOs that reap power ups after one hit. The main game sees the player go through five stages, and depending on the score achieved at the end of the level 2 and beyond, the player can opt for an easier or harder route, with a total of 11 individual stages. Arcade Mode features a save and retry feature that allows players to continue and restart the game from the level they were on. Ranking mode does not feature these options, but allows players to post their scores on the online leaderboards. Stage Mode (Free Play on PC) allows the player to replay any stage they have completed. Once the main game has been cleared once, Extreme Mode is unlocked. Extreme mode is only five stages long with no branching paths, since they are more difficult than the regular stages. Multiplayer The Xbox Live Arcade version of the game is the first version to include four-player co-op and versus multiplayer modes. Players can compete both locally and online over Xbox Live. On the DS, two players can compete against each other using either the Single-card download play, Multi-card play, or Nintendo WiFi Connection (via the Internet). The top screen is used to display the remote player's progress; there is also an online ranking system. The PSP version only allows local competitive play. Differences between versions Multiple player options for the DS version have already been mentioned above, but in gameplay terms both versions are the same, sharing the same levels, attack formations, similar graphics, and power-ups. However, the PSP version has crisper graphics due to the higher resolution implemented on the PSP. Also, while the DS version has a soundtrack composed and performed entirely by Taito's in-house sound team Zuntata, the PSP version features music