Retail CounterStrike will allow you to play ESF.
If its taking you to the CounterStrike game when clicking ESF icon, just click "Custom Games" from the CS menu. Then find ESF and click "activate" and then "done" and that should get you into ESF. If its bringing you straight to CS after clicking the ESF icon, your target direction is messed up. you need to have '-game esf' in the target box after the short-cut link.