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How Collins differs

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This page describes how Collins differs from NWL as a playing lexicon, and is part of our introduction to Collins (SOWPODS) in North America. For brevity, we will refer to the North American and International lexica, NWL2020 and CSW21, as NWL and CSW respectively.


Fundamentally, the game does not change. It is still the same Scrabble experience, as enjoyed by many worldwide. The overall game, and the basic strategy, such as finding a good score plus rack leave, are not changed by moving from NWL to CSW. In other words, it will still feel like the same game, just one with more words. If one were handing out a sheet of tips for new players, the same sheet could be handed out for CSW as it has been for NWL. There is a far greater difference between the kitchen table and the club than there is between the two lexica.

So the differences are not in the fundamentals, but in the details. The extra words are the most noticeable, and because there are so many of them, you will use them, particularly the short ones.

Challenge rule

After the words, the next biggest difference is the challenge rule: CSW games are generally not played to double-challenge, but with a points penalty. This is not intrinsic to the lexicon (the international WESPA rules do in fact allow double challenge, if desired), but has emerged as the de facto standard between no penalty at all, as played in Britain, and loss of a turn. In looking at the differences in more detail, we thus start with the challenge rule. The words are described in Important Collins words.

The altered challenge rule compared to the North American double-challenge rule is as follows:

  • If your opponent makes a play, you challenge, and their play is good, instead of losing your turn, the opponent gains points
  • Typically, this is 5 or 10 points per word challenged
  • After you have made an unsuccessful challenge, it is still your turn
  • If you challenge correctly, the rule is the same as North America: the opponent loses their turn and their incorrect play is removed from the board
  • The determination of move acceptability is done in the usual way: the play is ruled either acceptable or not, regardless of the number of words challenged. Which individual words are good or bad is not revealed

So if you, say, challenge two words, the play is ruled acceptable, and the penalty is 10 points per word, the opponent gets an extra 20 points, but it is still your turn.

Note, however, that there is a subtlety. Like North American double-challenge, the rule still applies on the final move. But, unlike double-challenge, the penalty still has an effect (you cannot lose a turn if the opponent has played out because there are no more turns). So the free challenge when the opponent plays out is lost. The opponent can, therefore, still gain the penalty of 5, 10, etc., points if you challenge incorrectly, which something to keep in mind if it is a close game.

It is not yet clear whether North American CSW games will ultimately end up as penalty rather than double challenge, but the current norm is a 5 or 10 point penalty.

It is also worth noting that with online play another form of challenge rule has become more popular: void challenge. In this form, the user is not allowed by the software to play an invalid word, and can check the validity of words before they make their play. This form of challenge rule is unaffected by which lexicon is used.

More choices of plays

Generally, there will be more choices for each play in CSW. The increased number of 2-3 letter words and hooks means there are often more possibilities to make overlapping plays, or play a bingo. While in some situations increased hooks can make it harder to block the board, in other situations increased overlaps can make it easier to play without creating openings: while a high scoring open game can thus be played, this style of play is not forced upon the player, because board areas with a dense covering of words with few openings can be created.

A consequence of the extra choice of moves is that there may be less time to think about each individual play than in NWL, which could be said to place a higher premium on play finding than on the strategic merits of individual moves versus each other. However, the number of possible plays and scope for strategic thought about each one vastly outweighs what can actually be achieved by any human player in a real game situation in either lexicon. So the perceived balance between the two things ultimately comes down to personal preference.

Some of the most significant sources of extra word choices are:

Two letter words
There are 20 extra two letter words in CSW21: CH, DI, EA, EE, FY, GU, IO, JA, KO, KY, NY, OB, OO, OU, ST, UG, UR, YU, ZE, and ZO. Note that the letter C therefore now has a two letter word, CH, but there are still no two letter words containing a V.
JA, ZE, ZO, and more threes, such as JAI, QIN, EXO, and ZEA, mean there is more potential for a 50- or 60-point J, Q, X or Z play. While sometimes your opponent might get these, in a game it is more likely to even out because they occur more often: your opponent may get one, then you get one too.
Vowel dumps
Short words with numerous vowels have a greater variety, including such examples as AIA, AUA, AUE, and EUOI.
There will be a playable bingo more often. Some high probability sets of letters that make no words in TWL now make a playable word, such as OTARINE, ETAERIO, ROASTIE, and ORIGANE. Of course, many combinations, such as ADEILNR or ADEILNT, still make no words.
CSW contains both more words and more meanings, so some words in NWL that do not take an S now do, e.g., ATS, OIS, AVAS, FEWS.
Comparatives and superlatives
CSW is more generous in allowing -er -est or -ier -iest inflections, e.g., FAVE, FIE, FOU, GEY, OORIE, or QUARE make FAVER, OORIEST, etc. Some of these are now-allowed comparatives/superlatives, others are from added meanings.
A particularly large addition is that more -INGS words are good. Some of the perhaps surprising omissions from NWL, such as GRADINGS, are good in CSW.
Other inflections
Other extra inflections follow similarly, e.g., some TWL words that are adjectives or nouns in NWL become nouns or verbs in CSW.

For more on the words, see Important Collins words.

Fewer exchanges

For the same reason that there are more choices, it is also usually more feasible to be able to make a play rather than be forced to exchange. The increased number of two letter words and other short words such as vowel dumps often mean that there is a play that is better than exchanging, even if it only scores 10–20 points. Often this is because the play uses the same or similar tiles to what would have been exchanged.

Can catch up from behind

In an NWL game, if a player bingos a couple of times quickly early in the game, their strategy is often simply to close down the board and make it difficult for the opponent to catch up. While the same block-when-ahead principle applies to CSW, because there are more words, it is often possible to create more chances to catch up again, through the increased numbers of possibilities for creating hooks, and the extra 2-letter words making it more likely that a bingo lane is available. Thus, the game is rarely “won” after just a few moves.

A converse to this is that sometimes the opponent can run away to a big score with many bingos, and you are powerless to stop them. Those who have played CSW against a top level computer player can attest to this!

Higher game score

Game scores are higher, although not by as much as one might expect. A top-level player, or the computer, will average about 425 points a game in NWL against an equally matched opponent. In CSW, they will average about 450. This is approximately a 6% difference, or about 2 points more per move. Of course, in games with unequal opposition, scores can be lower or higher in either lexicon.

Harder to play invalid words

The challenge rule, described at the start of this page, generally means that it is harder to play and get away with invalid words (phoneys). In particular, an expert player cannot just put down anything against a novice, because the novice can still challenge without risking the loss of their turn. Therefore, for a new CSW player facing an expert, this “bluffing” aspect is not as intimidating as under double challenge. However, experience shows that the non-double-challenge rule is by no means trivial: many phoneys can and do still get played, and point penalties from lost challenges can alter the game outcome. The purpose of the penalty is to retain the stop-and-think aspect of the double challenge, but to keep the onus on the player making the move to play valid words, because if you play a phoney and it is challenged, you do still lose your turn.

(In fact, even with free challenge, as in Britain, there is still the potential penalty of loss of one's own confidence for challenging valid words, especially if done several times in a game.)

Balance between defense and offense is shifted

There is a prevailing opinion that CSW encourages a more offensive rather than defensive playing style, favoring word finding rather than considering the strategic merits of different moves. This is because it generally seems easier to just keep scoring, with less regard for board position, or what the opponent does. However, it is not clear exactly to what extent this is really the case, compared to simply playing the same open style in NWL for the majority of the game. Given the prevailing opinion, it seems likely to have some truth to it, but little empirical or quantitative evidence has been presented. Both CSW and NWL provide rich strategical possibilities, far more than anyone can analyze completely during the course of a game, for a variety of playing styles.


While playing CSW is not identical to playing NWL, the game as known and loved by thousands of tournament players across North America is not fundamentally changed by playing CSW.

Please direct comments about this page to its author, Nick Ball.