Something

                UInt16[,] roomCollisionGraph = GetRoomCollisionGraph(level, room1);

                int posX = ((int)room1Coll.dwPosGameX - (level.dwPosX * 5));
                int posY = ((int)room1Coll.dwPosGameY - (level.dwPosY * 5));

                for (int yd = posY, ys = 0; ys < room1.dwYSize; yd++, ys++)
                {
                    for (int xd = posX, xs = 0; xs < room1.dwXSize; xd++, xs++)
                    {
                        if (ys == 0 && xs == 0)
                            levelCollisionGraph[xd, yd] = 0x55;
                        else
                            levelCollisionGraph[xd, yd] = roomCollisionGraph[xs, ys];
                    }
                }