If you are unable to proceed in game due to invisible wall or bouncing NPCs for example, please enable Vsync in game options(while in main menu select Options - > Display - > set Vsync to: ON).
Alternatively, please right-click on shortcut -> select properties and at the end of target line add: -RenderProfile_MaxFps 60 , so the entire line will look similar to this: "C:\GOG Games\Far Cry 2\bin\farcry2.exe" -RenderProfile_MaxFps 60
If you are using GOG Galaxy, please choose the game, press MORE -> Settings, select: Add command line arguments, type: -RenderProfile_MaxFps 60 in the box and then press PLAY.
There is also a mod called Far Cry 2: Redux which solves many bugs. You can find it HERE.
Please download this mod and copy-paste contents to the game installation folder(default: C:\GOG Games\Far Cry 2). If you are using GOG Galaxy, please press MORE -> Manage Installation -> Show Folder.