The best way to import .flame files to Chaotica is via the clipboard. First, copy the XML from Apophysis using either ctrl+c or Edit > Copy. Then, paste to Chaotica using either ctrl+v or Edit > Paste XML from clipboard. At this point, Chaotica will start rendering your fractal.
Troubleshooting Non-Matching Flames
Some Apophysis features are not supported by Chaotica, chiefly "3D hack" transforms and settings (including 3D camera settings such as pitch and depth blur). Check to make sure non-matching images do not use these features.
Missing or misbehaving plugins are the chief cause of incorrect renders. For more information on plugins, see Using Apophysis Plugin .DLLs.
Occasionally a difference in renders is due to imaging. Chaotica's imaging is similar to that of Apophysis/Flam3, but not identical. These differences are not severe render issues; they are superficial and generally do not even require restarting the render. Most often, increasing the brightness is an effective way to make the imaging match an Apophysis render.
Additionally, many artists make the final imaging itself part of the artistic process, experimenting with curves and producing something wildly divergent from Apophysis's render.