Simply type in the codes while playing:

 costa del dosh       Unlimited money
 quick quick quick!   Fast Build
 all buildings        Unlock All Buildings

 Press

 [Alt][Shift][$]      $5000
 [Shift][Alt][F10]    All mission levels
 [Shift][Alt][F9]     All sandbox levels
 [Shift][Alt][U]      All levels

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 Unlock All Scenarios

 While at the Main Menu, hold [ALT] + [SHIFT] and type

 allbuildings

 This will unlock all scenarios in both Mission and Sandbox modes.