We've put a lot of time into developing XY7 and hope you won't have too many problems. However some trouble-shooting tips are given below. Please post on our forums if you need further help.
The tilt calibration is normally performed at the start of each level. If you'd prefer you can change this on the settings screen (so it only calibrates once).
You can recalibrate at anytime during a level by pausing the game. Then select the recalibrate button.
The tilt movement works best when the device is held in front of you with the top of the screen tilted up (from a flat position). If the XY7 ship seems to be stuck or not moving smoothly try re-calibrating ensuring the device is held as described here. Make sure you hold the device steady whilst the calibration is happening (do not move the device).
XY7 has three difficulty settings. The difficulty can be changed on the settings screen.
Easy - you don't lose ship upgrades when you die.
Hard - you will lose ship upgrades when you die if you can't afford the salvage fee.
Insane - you can lose upgrades and everything moves and shoots faster!
If you are using a iOS4 device that has multi-tasking quit as many apps as possible before running XY7. See here for instructions on quitting apps.
For faster performance turn off high resolution mode in the XY7 settings screen.