For the Washington Redskins, it comes down to one game, several ifs and one intriguing question: will George Allen be making his final appearance as the team's head coach today against the Los Angeles Rams?

Allen, who still has not signed that four-year extension to his contract, said yesterday, "I think not, I hope not," when asked if today's 1 p.m. affair would be his last home game as coach of the Redskins.

"It's my decision. I felt it wasn't that important. Whatever the details, my attorney can work it out with the Redskins. I hate to even think about it because it isn't that important. The most important thing is to play good football and win. So I'm not thinking that way (that he will not be here in 1978.)"

Does that mean he plans to return in 1978?

"Yeah, we like it here," he said. "I'm proud of our team. I like our organization. I like our players and I like my staff. They've worked hard and done a good job.

"It just happened to turn out this way. When your attorney recommends not to sign until a couple of things are straightened out . . . so if you have an attorney, you've gotta go by him. This to me should be the last thing at the bottom of your article."

And yet, Allen's future in Washington seems inexorably tied to the outcome of today's game against the NFC Western Division champion Rams, as well as games involving the Minnesota Vikings and Chicago Bears in the following 24 hours.

If the Redskins can slip into the playoffs - and all manner of combinations can make that happen - Allen's position obviously would be strengthened when the coach, his attorney, Ed Hookstratten of Los Angeles, and team president Edward Bennett Williams continue negotiations.

Both Hookstratten and Williams have chosen not to comment on Allen's contract problems in recent months, though NFL sources continue to say the impasse is based almost totally on financial control of the football operation.

Allen wants more, those sources say, and Williams apparently is unwilling to yield.

"I don't think anyone really knows what's going to happen," tight end Jean Fugett said. "You hear all the talk, some of the guys say he's going, other guys say he's staying. I do know this, nobody's talking about winning this game for the Gipper or anyting like that. We just know we've got to win it to keep breathing."

A redskin victory guarantees nothing, of course, because if the Vikings defeat Detroit tonight and Chicago downs the New York Giants Sunday, the Redskins will celebrate Christmas at home. (See accompanying box for all other possibilities).

The oddsnakers say the Rams will prevail by four.

If the Redskins do manage to attain the wild-card berth, their opening-round opponent would be the Rams, in Los Angeles, on Dec. 26. And that leaves another intriguing question about today's affair.

Will the Rams go all out, knowing they could face this same Washington bunch a week from now? Or will they rest injured players, stay basic and do just enough to win, or at least avoid getting embarrassed?

The Rams also would seem to benefit if the Redskins do make the playoffs. It seems likely Los Angeles would prefer to play a Washington team that has struggled all year on offense, rather than a Chicago team that features the game's most devastating runner, Walter Payton.

The Rams have been insisting all week they do not intend to roll over.

"We've got a lot of pride, and we'd like to keep our momentum going into the playoffs," said Ram center Rich Saul, the twin brother of Redskin offensive guard Ron Saul.

"Sure I'd like to see my brother make the playoffs. But he knows I'm going all out when I'm on the field, and so will everyone else on our team. That's promise."

"It's hard game to figure out," Allen admitted yesterday after his fourth closed practice of the week. "This is probably the best overall Ram team in the last five years.

"They have more stability at quarterback; Pat Haden's done an outstanding job. They have more speed all the way around, and their defense, I believe, is No. 1 in points allowed in the league."

Actually, the Rams have given up seven more points, 129, than the NFL-leading Atlanta Falcons. But L.A. has huge statistical advantages over the Redskins in almost every offensive and defensive category.

The Rams average 330 yards of offense, the Redskins 259. They have scored 34 touchdowns this season, the Redskins 17. They have held opponents to an average of 256 yards per game, the Redskins have yielded an average of 294.

Haden leads the NFL in passing with a 58.7 completion average, 11 touchdown tosses and only five interceptions. Running back Lawrence McCutcheon, who probably will start but not play the entire game, already has rushed for a team-record 1,213 yards.

The Redskins will attack the NFC's fourth-ranked defense with Billy Kilmer at quarterback and a hurting Mike Thomas at tailback. Thomas missed practice most of the week because of an aggravated ham string injury, but Allen said he expected him to start this afternoon.

Allen even left a glimmer of hope that defensive tackle Bill Brundige may be able to play, though he was still limping badly on a sprained left foot and bruised left knee yesterday and is listed as very doubtful for actioN.

After what could well have been his team's final practice of the 1977 season, Allen also was insisting, "I think we still have a very good chance (to make the playoffs).

"The most important thing is for us to play well and win. Other than that, it doesn't mean much."

And if the Redskins do get into the playoffs, how will Allen celebrate?

"We'll all have blackberry brandy on the rocks," he said.