user11425: I am looking for a really-bad-by-design chess engine, compatible with Arena chess GUI. Not just lowering engine power..
I have tried lowering Stockfish's power, and it didn't suit my needs, so I am looking for a weak one!

user11425: I found it! UFIM works well for my purpose!

user825: You have a whole list at http://www.computerchess.org.uk/ccrl/4040/
If you're looking for a weak engine, I'd suggest:

Predateur 2.2 64-bit
MicroMax
CupCake
BikJump 

I know those four engines work and run smoothly, although they're quite weak (which is exactly what you want!). Any Elo 2000 rated human player can trash them easily.
__ My Recommendation __
If your engine can't even beat the lowest Stockfish level, maybe it'd be a better idea to focus on your engine, such as adding easy technqiues like null-move pruning. As an average human player, I can consistently beat the lowest Stockfish level, it plays around 1500-1600 level. Even the engines I mentioned might be too strong for you.

11425: <p>I am looking for a really-bad-by-design chess engine, compatible with Arena chess GUI. Not just lowering engine power..
I have tried lowering Stockfish's power, and it didn't suit my needs, so I am looking for a weak one!</p>
 11425: <p>I found it! <a href="https://chessprogramming.wikispaces.com/Ufim" rel="nofollow noreferrer">UFIM</a> works well for my purpose!</p>
 825: <p>You have a whole list at <a href="http://www.computerchess.org.uk/ccrl/4040/">http://www.computerchess.org.uk/ccrl/4040/</a></p>

<p>If you're looking for a weak engine, I'd suggest:</p>

<ol>
<li>Predateur 2.2 64-bit</li>
<li>MicroMax</li>
<li>CupCake</li>
<li>BikJump </li>
</ol>

<p>I know those four engines work and run smoothly, although they're quite weak (which is exactly what you want!). Any Elo 2000 rated human player can trash them easily.</p>

<p>__ <strong>My Recommendation</strong> __</p>

<p>If your engine can't even beat the lowest Stockfish level, maybe it'd be a better idea to focus on your engine, such as adding easy technqiues like null-move pruning. As an average human player, I can consistently beat the lowest Stockfish level, it plays around 1500-1600 level. Even the engines I mentioned might be too strong for you.</p>
