Frequently asked questions

Welcome to Explo®! Explo is a crossword-style word game that combines fun, a healthy workout for your brain, and a good time with friends.

Here are answers to some common questions about Explo’s functionality. If you have a question that is not answered here, you can send it to contact@explowordgame.com and we will do our best to reply.

What words are allowed in Explo and why?

For English, Explo allows words either from the OTCWL2014 word list (U.S. and Canadian English) or SOWPODS dictionary (UK/Combined English).

OTCWL2014 stands for Official Tournament and Club Word List, 2014 Edition. It was defined by the North Americal Scrabble® Players Association (NASPA) and used for competitive play in the U.S. and Canada.

SOWPODS is a combination of the two abbreviations OSPD (Official Scrabble® Players Dictionary) and OSW (Official Scrabble® Words). It is a dictionary often used for Scrabble® tournaments outside the U.S. and Canada.

What’s the difference between the four robots?

Freyja, the strongest robot, always chooses the highest scoring move in each position. However, she does not think tactically. For example, she does not consider whether her move opens a triple-word square for her opponent.

Idun, the second-strongest robot, chooses randomly from one of the 20 highest-scoring possible moves.

Frigg, the third-strongest robot, chooses one of the 20 highest-scoring possible moves from a dictionary of about 35,000 common words. She is adaptive, so she also adjusts a bit to the ability of her opponent.

Sif, the easiest robot, chooses one of the 30 highest-scoring possible moves from a dictionary of about 20,000 common words. She is adaptive and adjusts her difficulty level to the ability of her opponent.

Freyja and Idun have the entire dictionary at their disposal, i.e. all of the SOWPODS or OTCWL2014 word lists.

Although Frigg’s and Sif’s vocabulary is limited, you can still play all permissible words against them.

I think the robots are drawing better tiles than I am. Why is that?

That is just an unlucky coincidence. The robots draw letters from the bag according to the same algorithm as you. (The algorithm is the “formula” in Explo software that is responsible for selecting letters from the “bag” at random.)

The robots are playing words that I am not allowed to use. Why is that?

It is an absolute rule that if an opponent, human or robot, can play a word, then you can too (and vice versa). The same dictionary applies to everyone playing in the same language, always!

The opponent hasn’t played for many days. How can I get rid of “dead games”?

You can force an opponent to surrender when 14 days have passed without a move in a game. When that happens, the inactive player loses all their points, and possibly the game as well. You, however, keep your points intact.

After 12 days without a move, a red arrow appears next to the game in the inactive player’s ongoing game list. He then has two days to respond. If he does not, the red arrow also appears to you. If you open the game by clicking on it, you will see a red button at the bottom of the screen, below the board, that says “Force resignation”.

If you tap that button, you have won by forced surrender. There are no time limits on such coercion, after 14 days have elapsed.

Where can I see the two-letter word list?

If you touch the button marked AB below the game board, the list will appear.

You can select tabs that show the list sorted by the first letter or the second letter.

Can I get rid of the sounds that are heard in Explo?

Yes, you can mute the sound in the settings. Choose the settings by touching the gear icon in the top right corner, and then the heading Preferences. Underneath that is a switch labelled Play background music. Disable it and the music will be turned off.

How are the points calculated?

The points for each move are calculated in the same way as in traditional crossword board games. The main rules are:

• The tile values (points) of all complete words that your move forms, whether they are new words or additions to words that were previously on the board, are added together. Words can be formed both horizontally and vertically. Of course, all words must be permissible.
• If you place a tile on a light blue or dark blue square, the tile value of that tile is multiplied, i.e., doubled on a light blue square and tripled on a dark blue square. The multiplied points count both in a horizontal and a vertical word if the square is part of two newly formed words. For example, if you manage to put a Q, which has a tile value of 12, on a dark blue square (tripled tile value) so that it is part of two words, you get a total of 12 x 3 x 2 = 72 points just for that one Q – and then the other letters are yet to be counted.
• If you place a tile on a light orange or dark orange square, the point value of the entire word that the tile is part of is multiplied, i.e., doubled on the light-colored and tripled on the dark-colored square. The multiplication applies to both a horizontal and a vertical word if the square is part of two newly formed words.
• For each newly formed word, tile values, whether simple or multiplied (on light blue or dark blue squares) are first calculated and added together. After that, the word value thus obtained is multiplied up if new tiles in the word are on light orange or dark orange squares. Note that a word can lie across two word multiplier squares, which then give a total of four times or even nine times the word value.
• Multiplier squares are only active during the move in which a tile is laid on them. After that, they lose their effect. Tiles on them have a nominal tile value if they are part of words that are later laid down.
• Empty tiles, which can represent any letter of the player’s choosing, yield no (zero) tile points.
• If a player manages to play all seven tiles in the rack in one move, it’s called a bingo. A bingo gives a 50-point bonus.
• If you pass or choose to exchange tiles, you get no points in that round.

What are Elo points?

Explo calculates so-called Elo points (see here) for all players and the robots. The calculations are done once a day, and apply to games that had been concluded at midnight.

The points are an indication of player strength, but should not be taken too seriously.

New players initially receive 1200 Elo points. The number of points increases each time a player wins a game, but decreases with a loss.

Elo points work broadly in such a way that based on them, a forecast is made about the outcome of a game, or more specifically about the winning probability of each player. When the game has concluded, Elo points are moved from the loser to the winner, in proportion to the deviation of the result from the forecast. You could say that the system is constantly correcting its own forecasts and trying to move them closer to the actual results of games.

Where can I see the Elo points?

You can see your own Elo points within the orange header at the top of the main Explo screen.

The Elo points are located in the bottom right corner of the header.

How are the Elo points calculated exactly?

If E_a are the Elo points of player A and E_b are the points of player B, the system calculates
S_a = 10 ^ (E_a / 400) and S_b = 10 ^ (E_b / 400).

The winning chances of A are then L_a= S_a / (S_a + S_b), but the winning chances of B are L_b = S_b / (S_a + S_b).

If A wins the game, he gets 20 * (1 – L_a) extra Elo points, but if he loses the game, he loses 20 * (1 – L_b) = 20 * L_a points as L_a + L_b = 1. The same applies to B with opposite signs.

Example: A has 1200 Elo points but B has 1600.

S_a = 10 ^ 3 = 1000.

S_b = 10 ^ 4 = 10000.

L_a = 1000 / 11000 = 9.09%.

L_b = 10000 / 11000 = 90.91%.

B is thus considered 10 times more likely than A to win the game. If that is the result, B gets 20 * 9.09% = 2 Elo points extra, as the victory is very close to the system’s forecast. Conversely, if B loses, he loses 20 * 90.91% = 18 Elo points, which A gets – as A is then considered an underrated player who should move closer to B in point number.

Here are some examples of the Elo system’s prediction of players’ winning chances based on their point difference:

Elo Point Difference	50 pts	100 pts	200 pts	400 pts
Higher-ranked Player	57%	64%	76%	91%
Lower-ranked Player	43%	36%	24%	9%

The Elo system in Explo only looks at victory, draw, or loss. It does not matter by how many points the match was won or lost. A draw is considered as half a victory for each player.

The exception is that the first 10 games of beginners only affect their own Elo points, not their opponents’ (unless they are also beginners). It is therefore safe for more experienced players to compete against beginners, even if their Elo points may be wrong to start with.

Why are Elo points missing from my latest games?

The Elo calculations take place around 03:00 UTC each night and are based on games that had concluded at midnight.

Why are there two Elo lists?

One list considers all games, also against robots. The other list is only calculated based on games between humans. The Elo status of players can be different on these two lists.

Why don’t the Elo points change at the end of the game?

Games against beginners, i.e., players who have not yet finished 10 games, are not taken into account in the Elo points of more experienced players.

What do I gain from being an Explo subscriber?

Subscribers to Explo enjoy the following benefits:

• An unlimited number of games in progress simultaneously, instead of a maximum of three.
• The ability to play against Idun and Freyja, the two most advanced robots.
• Access to a summary after a game has ended, showing the best moves that were possible at each turn.
• They can challenge other players in Pro Mode with manual challenging of words, without automatic indication of word validity.
• Subscribers are awarded a blue crown that shows they are friends of Explo!

How do I stop being a subscriber?

It’s simple: you choose Settings (the cogwheel icon in the top right), then the heading Account and then touch the button Manage subscription. But we would be quite sad to see you go!

What is Pro Mode?

Subscribers can challenge other players in Pro Mode. In Pro Mode, there is no green indicator that shows whether words are valid or not. Any word can be played. It is up to the opponent to challenge a play that he considers wrong.

An opponent’s move is challenged by clicking on the red button with a white ban sign.

If the opponent’s move is invalid, i.e., any word it forms is not in the current dictionary, it is removed from the board and the points that the opponent got for it are subtracted back. Then it’s your turn; the opponent has forfeited the round and gets no points for it.

If the opponent’s move is however valid, and the challenge is therefore illegitimate, the opponent gets 10 extra points in damages. It’s still your turn.

Pro Mode is intended to mimic playing on a traditional board. Challenge rules are in accordance with common competition rules.

How do I challenge an opponent in Pro Mode?

If you are a subscriber to Explo, you can challenge other players to games in Pro Mode, whether they are also subscribers or not.

Pro Mode is selected by an option on the screen that appears when you issue a challenge.

How do I delete my Explo account?

You can delete your Explo user account at any time by pressing the Delete account button located within the Settings menu (under the cogwheel icon in the top right corner), specifically in the Account section.

This deletes your current user account and erases your full name, e-mail address and profile image. To maintain other players’ data, Explo retains your nickname, game history and chats.

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Note: Scrabble® is a registered trademark. Explo in no way affiliated with or endorsed by the owners or licensees of the Scrabble trademark.