Have you forwarded 27055 UDP as well as TCP?
Yes, here's my netstat
root@oxioxivps:~# netstat -tulpn
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 188.209.52.70:27015 0.0.0.0:* LISTEN 9789/srcds_linux
tcp 0 0 127.0.0.1:3306 0.0.0.0:* LISTEN 1057/mysqld
tcp 0 0 188.209.52.70:27055 0.0.0.0:* LISTEN 18693/srcds_i486
tcp 0 0 0.0.0.0:21 0.0.0.0:* LISTEN 692/vsftpd
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 1013/sshd
tcp6 0 0 :::80 :::* LISTEN 1281/apache2
tcp6 0 0 :::22 :::* LISTEN 1013/sshd
tcp6 0 0 :::443 :::* LISTEN 1281/apache2
udp 0 0 0.0.0.0:27005 0.0.0.0:* 9789/srcds_linux
udp 0 0 0.0.0.0:27006 0.0.0.0:* 18693/srcds_i486
udp 768 0 0.0.0.0:27015 0.0.0.0:* 9789/srcds_linux
udp 0 0 0.0.0.0:27020 0.0.0.0:* 9789/srcds_linux
udp 0 0 0.0.0.0:27021 0.0.0.0:* 18693/srcds_i486
udp 0 0 0.0.0.0:60586 0.0.0.0:* 9789/srcds_linux
udp 0 0 0.0.0.0:27055 0.0.0.0:* 18693/srcds_i486
udp 0 0 0.0.0.0:13506 0.0.0.0:* 642/dhclient
udp 0 0 0.0.0.0:52697 0.0.0.0:* 18693/srcds_i486
udp 0 0 0.0.0.0:26901 0.0.0.0:* 9789/srcds_linux
udp 0 0 0.0.0.0:68 0.0.0.0:* 642/dhclient
udp6 0 0 :::17975 :::* 642/dhclient