Is there any way? Just cause two can be played by a card having 1 GB vRAM but Pixel Shader 3.
yes you can run that game but in midium graphics details
better to follow the recommendation to limit graphic card
If a game [engine] explicitly requires Pixel Shader 4 it won't run on a card that only supports PS 3.0.
If a game recommends a graphics card with PS 4.0 there is a (good) chance it is downward compatible to Pixel Shader 3.0 cards [using lower graphics settings or losing some "eyecandy"]
Steam has a good guideline that depicts the compatibility.
If the game suggests PS 4.0 but only requires DirectX 9.0c there is a good chance it will run with a PS 3.0 card.
If the game requires DirectX 10 in addition to PS 4.0 it is unlikely to be compatible with a PS 3.0 card.