user15958: I am new to the site and would appreciate help in this area.
At my current stage (beginner) I have started to draw or sometimes even beat the computer at low levels (ex. chess.com level1,2,3, lichess.org level1,2). One of these sites has an interesting feature that helps me a lot, it is a set of 3 numbers like a score. Here is an example of a game where I play White and I am behind 2 pawns (-2pts in material):
        +2.90 
        -1.78 
        -2.14 
        Stockfish.js 8 | depth=19

Which I interpret the following way: 

Positional score shows max=+2.90, which means that there is a tactic opportunity involved (overloading? removal of defender?...etc I must find out!).
If I see the opportunity and play correctly, I can materialize the advantage and win an important piece (maybe win a rook, or take the queen in exchange of one of my rooks)
If I miss the opportunity, the next score will be -1.78 (second best move) or -2.14 (third best move).
That is, the momentary positional advantage will disappear and the score will revert to the material strength (2 pawns behind).

Well, my problem is that I sometimes blunder and my score goes abruptly down to for instance -M2 [mate-in-2 for Black].
I lose the game :( because I did not realize that there was a mate danger (ex: last rank weakness or something like that).
The score of the site I am playing only shows the 3 best moves, not the WORST moves.
I am formulating this question here in the hope that someone knows other sites for beginners, with an engine that can be tuned to warn if there is a risk of blundering and being prematurely mated.
If I do not find such feature, well, I will have to be patient and continue with the learning process:). The frequency of blunders should decrease as I gain experience.
Thank you for your help.

user16641: If you want to be able to see the evaluation for the worst moves, you could download stockfish, run it, and enter: setoption name MultiPv value 499. To then evaluate a position, you would use the go command, such as go movetime (ms), go depth (depth), or go infinite.
The MultiPv option just allows you to view as many principal variations as you want, and for a sufficiently large number this is just all of the pvs.

user12449: Many engines have a "teacher is watching" feature which tell you if you make a bad enough move.  Lucas chess will provide a dialog which includes the options to make your move, the suggested computer move or provide a hint why your move is bad.
Most engines which shows lines, also let you adjust the number of line to include all lines available.

user27648: Not long ago I was looking for very similar thing, the closest I got was program called ChessTricks. The program is using a chess UCI engine to analyse different positions with the sole purpose of looking for traps and tricks.
Let's say for example that you are playing a game against the computer and you find yourself in a position where the computer is giving you a "free" piece, you being a lower rated player have no clue what is going on and proceed on taking the free piece. BAM!! all of a sudden you got yourself checkmated :( and you wonder what happened.
What this software does is pointing out to you and giving you a hint of what will happen if you take the "free" piece ( called sacrifice in chess), it analyses the position and looks for not only the best refutation but also the worst possible outcome which in the given example case was you getting checkmated.

user825: Showing only the worst moves for a position is not something you'll find. Computer engines are not appropriate for warning against risk of blunders. My suggestions:

Take back a move against computer if you make a bad move
Review your game

You're asking the question because you're afraid of losing. There's no shame to lose against a computer. You learn more by going back your game (or takeback) then explicitly being warned.

15958: <p>I am new to the site and would appreciate help in this area.</p>

<p>At my current stage (beginner) I have started to draw or sometimes even beat the computer at low levels (ex. chess.com level1,2,3, lichess.org level1,2). One of these sites has an interesting feature that helps me a lot, it is a set of 3 numbers like a score. Here is an example of a game where I play White and I am behind 2 pawns (-2pts in material):</p>

<pre><code>        +2.90 
        -1.78 
        -2.14 
        Stockfish.js 8 | depth=19
</code></pre>

<p>Which I interpret the following way: </p>

<ul>
<li>Positional score shows max=+2.90, which means that there is a tactic opportunity involved (overloading? removal of defender?...etc I must find out!).</li>
<li>If I see the opportunity and play correctly, I can materialize the advantage and win an important piece (maybe win a rook, or take the queen in exchange of one of my rooks)</li>
<li>If I miss the opportunity, the next score will be -1.78 (second best move) or -2.14 (third best move).
That is, the momentary positional advantage will disappear and the score will revert to the material strength (2 pawns behind).</li>
</ul>

<p>Well, my problem is that I sometimes blunder and my score goes abruptly down to for instance -M2 [mate-in-2 for Black].
I lose the game :( because I did not realize that there was a mate danger (ex: last rank weakness or something like that).
The score of the site I am playing only shows the 3 best moves, not the <em>WORST</em> moves.</p>

<p>I am formulating this question here in the hope that someone knows other <strong>sites for beginners, with an engine that can be tuned to warn if there is a risk of blundering and being prematurely mated.</strong>
If I do not find such feature, well, I will have to be patient and continue with the learning process:). The frequency of blunders should decrease as I gain experience.</p>

<p>Thank you for your help.</p>
 16641: <p>If you want to be able to see the evaluation for the worst moves, you could download stockfish, run it, and enter: <code>setoption name MultiPv value 499</code>. To then evaluate a position, you would use the <code>go</code> command, such as <code>go movetime (ms)</code>, <code>go depth (depth)</code>, or <code>go infinite</code>.</p>

<p>The MultiPv option just allows you to view as many principal variations as you want, and for a sufficiently large number this is just all of the pvs.</p>
 12449: <p>Many engines have a "teacher is watching" feature which tell you if you make a bad enough move.  <a href="http://lucaschess.pythonanywhere.com/" rel="nofollow noreferrer">Lucas chess</a> will provide a dialog which includes the options to make your move, the suggested computer move or provide a hint why your move is bad.</p>

<p>Most engines which shows lines, also let you adjust the number of line to include all lines available.</p>
 27648: <p>Not long ago I was looking for very similar thing, the closest I got was program called <a href="https://chesstricksapp.wordpress.com" rel="nofollow noreferrer">ChessTricks</a>. The program is using a chess UCI engine to analyse different positions with the sole purpose of looking for traps and tricks.</p>
<p>Let's say for example that you are playing a game against the computer and you find yourself in a position where the computer is giving you a &quot;free&quot; piece, you being a lower rated player have no clue what is going on and proceed on taking the free piece. <strong>BAM!!</strong> all of a sudden you got yourself checkmated :( and you wonder what happened.</p>
<p>What this software does is pointing out to you and giving you a hint of what will happen if you take the &quot;free&quot; piece ( called sacrifice in chess), it analyses the position and looks for not only the best refutation but also the worst possible outcome which in the given example case was you getting checkmated.</p>
 825: <p>Showing only the worst moves for a position is not something you'll find. Computer engines are not appropriate for warning against risk of blunders. My suggestions:</p>

<ul>
<li>Take back a move against computer if you make a bad move</li>
<li>Review your game</li>
</ul>

<p>You're asking the question because you're afraid of losing. There's no shame to lose against a computer. You learn more by going back your game (or takeback) then explicitly being warned.</p>
