Operation 7

[PMP]

Operation 7 Teaser Trailer

This is a Free Online FPS with good realism. Althought it looks similar to other of its genre like combat arms. It certainly raises the bar. It had some nice features:

• Complete weapon customization. You can change the barrel length and silence it, change buttstocks, foregrips, magazines and aiming devises. And modifications affect the weapon stats. For example, the longer the barrel, the more accuracy and range but less control and mobility.
• Anti lag system. The shots first tag the player and than deliver the damage. Meaning that even if someone lags, if you shot him, you shot him. And due to the difference between getting shot and dying you can kill people that killed you. Meaning you can kill  each other in a face to face shotting
• The iron sight are usable unlike Combat Arms. In sniping sights you can hold your breath to stabilize aiming. Snipers never kill with one shot except for the head.
• You can lean.

You can learn more on the websites:
Europe: http://operation7.fiaa.eu/default.asp
Americas: http://op7.netgame.com/

For me, this is the best free FPS I ever played.