No... op der Cloche d'Or.

Here is an Excel file with list of places in Luxembourg with their official names and names in Luxembourgish, as well as the article and preposition to use. Source.

A large choice of shows and cartoons in Luxembourgish is available at RTL Play.

It has both video and audio medias.

An ongoing work of Jérôme Lulling to put together some grammar rules; comes with exercises: http://www.grammaire.lu

Here are some videos of a guy (Youtube user Madsplay) playing different games and commenting in Luxembourgish:

And here is the group on Facebook.

Thanks to IceMemeVan#2650 from Discord who pointed this out.

During the COVID-19 lock-down, Jérôme Lulling started to make his Luxembogrish courses via YouTube and put recordings online. You can follow them on his user's page.

Look especially at videos with "Videochat" and/or "Lëtz léieren" in the name.

Jérôme Lulling has put online a number of materials for learning Luxembourgish. One of them are on LearningApps.org platform: http://www.exercice.lu (redirects here).

Games/quizzes are split in categories

Different type of games

And many more...

Here are  randomly generated crosswords using LOD dictionary data. The clue of each word is a translation.

Here are some in English, some in French, some in German and some in Portuguese. Each file has 100 crosswords and their answers.

If these are not enough, we can generate more.

A couple of days ago I found that there is a resource similar to this site (because... everything has been already done before), that has a number of links that could help in learning Luxembourgish. It's here: https://www.reddit.com/r/learnluxembourgish/wiki/index (and of course its parent page with discussions).

There is also a discord server if you want to chat.

On 15th of November 2019, the orthography of Luxembourgish language had been updated. This page contain the rules and exceptions on how to write words in Luxembourgish.  

Moreover, at https://ortho.lod.lu/ one can practice the spelling:

But you can also check the spelling of your non-confidential texts online (some information is here). Good luck with the spelling.

If you want to have LOD.lu dictionary data offline, here is a version of this data in Stardict format: lod.zip.

Under this link you can find a couple of application names for Android and iOS that support this dictionary.

Detailed instruction on how to install it are to follow (contributions are welcome).

EBPocket Basic

It is a one of the least straight-forward apps to add the custom dictionary as it starts an FTP server through witch you can upload custom dictionaries (with some other apps you can just put a link and it will download it for you and do the rest...).  Following some screenshots on how to do it for EBPocket Basic (iOS) and a Windows PC. Completely similar procedure can be applied for EBPocket on Android.

1. Download and extract dictionary files

Open Internet Explorer, and put the link https://letzebuergesch.review/ufiles/lod.zip (also mentioned at the beginning of the article) into the search bar:

and then press "Enter". It will ask what to do:

Choose "Open". It may ask what software to use:

You can use File Explorer:

Drag and drop "lod" dictionary, for example, into "Downloads" folder on the left. It will extract the dictionary files there (as this particular app requires unarchived dictionary):

Now we have dictionary ready to be written to the application's repository.

2. Install and run EBPocket + run the FTP server

This is one of the dictionary applications that support custom data, look for it in your AppStore/ GooglePlay... Note that some other applications are mentioned here.

After you have run EBPocket (Basic/Free/*), head to the settings (a button at left-bottom):

Select FTP Server

and run "Start" on the top-right:

Very important note: your computer as well as the smartphone should be connected to the same (WiFi) network, otherwise you won't most likely be able to connect these two.

After you have started, you will see the IP Address and the Port No.:

These two you will need to connect to it from your computer (in the screenshot's case, the IP is 192.168.178.20 and the Port is 12345.

Another important note: you need to keep app running. If the screen switches off, you might need to Stop and Start the FTP server (the same Top-Right button's position).

3. Download and start FTP client

As mentioned, we will need an FTP client. Download FileZilla from here (feel free to use any other client if you are familiar with it) and install.

After you start the FileZilla,

put the IP address and Port number at "Host" and "Port" fields correspondingly:

Click "Quickconnect". If everything is fine, it will warn you about unsecure connection:

You should click "OK" (we don't transfer any confidential data).

If something did not work, have a look at two "Important Notices" from the previous section, or drop a comment.

Normally you should see the content of EBPocket in the FileZilla. After double-clicking on EBPocket it should look like this:

Now, locate on the left side your Download directory and drag/drop "lod" subdirectory into EBPocket on the right. It will start the transfer as you see at the bottom of the screenshot:

When it's done, you transfered the dictionary to your smartphone and cna stop the FTP server.

4. Select the Luxembourgish dictionary in the app

Just in case, you might want to restart your EBPocket app. After it started again, look at bottom-right - there is an icon with a couple of books, this is to manage dictionaries. Click it, and you should get something like:

The only thing that's left is to choose the Luxembourgish one by tapping it. To check, you can open this setting again, and you should see the "✓" sign on it:

You can use the dictionary now.

A luxembourgish educational portal oli.lu has among different training material for school students a set of more than 1500 pictures with annotation in luxembourgish:

There is also a vocabulary learning section (it has multiple languages to choose from):

and a similar game in a picture form:

If you have kids, they might even like it.

Here is a series of "Smart-books", each is a separate story and each has just 36 pages:

And costs not too much, 3€. Can be bought, for example, at Ernster. Recommended by Ratna.

A small online games about knowledge of Luxembourg and Luxembourgish language: https://www.rtl.lu/kultur/sprooch

On the same page you can find crosswords in Luxembourgish:

Here it is: https://spellchecker.lu/online-checker/

If you need to check syntactically your text, or a text from RTL, paste there and press the "ABC" button.