Construct is a free powerful and easy to use development software for both DirectX 9-based games and applications,in a WYSIWYG environment. It includes an event based system for defining how the game or application will behave, in a visual, human-readable way - easy enough for complete beginners to get results quickly. Optionally, advanced users can also use Python scripting to code your creations.
Construct (Classic) is easily one of the best 2D game making engines out there and with a price tag of $0 it makes it one of the cheapest as well.
Summary
Pros:
Create games with no programming knowledge (Really this time! :) )
Support for Python scripting when you need even more firepower!
Contains built-in objects such as sprites and built-in behaviors like bouncing ball, RTS, physics, turrets etc which speeds game development.
Supports advanced effects like pixel shaders right out of the box while still allowing games made with it to support computers that don't support pixel shaders.
Comes with convenient features like 'families' to eliminate the need to create duplicate logic for multiple objects that share common behaviors
Cons:
One of the biggest problems is limited tutorials and no official manual, there is an unofficial manual in the forums which helps a bit though. Construct Classic has many useful features but need a little explanation before they can be put to good use.This is probably the biggest barrier to better adoption rates by people who want to make games with little or no programming.Also the lack of offline help that should come with construct program (as part of the download) but doesn't isn't such a great thing either.
Limited platform support: Construct Classic only supports compiling to windows executable format (exe)as of writing, granted windows is the most prolific, but it isn't the only operating system.
Construct Classic is very powerful and can be used to create some very impressive games, if you are familiar with Click team products like The Games Factory and Multimedia Fusion, then you will feel quite at home as Construct 'borrows' many elements from those products.
Don't underestimate this powerful little program. :)
BTW To make sprites with transparent backgrounds, fill the areas you want to make transparent with Magenta(Red 255,Green 0,Blue 255)