Level select:
Highlight either the "R-Type" or "R-Type II" options at the title screen. Quickly press L2(10), R2(10). Begin game play and press Start. Any level, including the ending FMV sequences, may now be accessed through the "Stage Select" option.

Speed select:
Press Start to pause game play in R-Type or R-Type II. Hold L2 and press Right, Up, Right, Up, Down, Left, Down, Left. Then, press Circle to increase or X to decrease the speed.

All weapons:
Press Start to pause game play in R-Type or R-Type II. Hold L2 and press Right, Up, Left, Right, Down, Left, Up, Right followed by one of the following buttons for various weapons: Triangle, Square, X, Circle, or R1.

Extra credits:
Repeatedly press Select at the title screen of any R-Type game to get up to 99 credits. This may also be done at the countdown on the game over screen to continue.