PPTP & broadcasts - need help

I want to make my firewall into a PPTP server so that a friend of my
son's can get his Windows PC on our LAN - this is to make it easier for
them to play games together.

I successfully installed PoPToP, the remote PC can connect and gets a
valid IP on my LAN. I turned on proxyarp, wanting the remote PC to act
like it was on my LAN. I can ping it when it connects, but ping
broadcasts do not reach it.

My internal network is as follows:
192.168.200.1 firewall/gateway internal IP (also localip for ppp0)
192.168.200.11-15 local NATed PCs behind firewall
192.168.200.128 remote PPTP IP address

The man page for pptpd.conf reads, in part:

ROUTING CHECKLIST - PROXYARP
Allocate a section of your LAN addresses for use by clients. In
/etc/ppp/options.pptpd set the proxyarp option. In pptpd.conf do
not set localip option, but set remoteip to the allocated address
range. Enable kernel forwarding of packets, (e.g. using
/proc/sys/net/ipv4/ip_forward ).

The server will advertise the clients to the LAN using ARP,
providing it's own ethernet address. bcrelay(8) should not be
required.

I did as suggested above, did not set a localip, did set the remote ip.
This didn't work, as the localip was then automatically to 192.168.0.1
and this would have required a whole bunch of new firewall rules. I
specifically set the localip to 192.168.200.1, which is the same as my
firewall/gateway's internal ethernet IP address. When set as such,
pings work as well as explicit TCP/IP connections. Broadcasts do not
seem to work at all - no broadcast pings work, and games that rely on
broadcasts do not seem to work. Broadcasts seem to go from ppp0 to the
LAN, but not from the LAN to ppp0.

Is there any way to get the remote PC truly to look like it is on the
LAN? I want all TCP/IP and UDP broadcasts to flow both ways.