itch.io

(direct link to the image in the auction above)
i-img1200x675-17311108142596qblovz44420.jpg (1200×675)

I found at least a good quality picture of the front of the booklet, I'll keep looking to see if there's better scans out there.
＜USED＞学研＜平安京エイリアン＞LSIゲーム・・...

学研　平安京エイリアン LSIゲーム - メルカリ

I found some scans of the instruction card & booklet, though some of the images might be a bit blurry.

Amazon.co.jp: QAZ13247 学研 平安京エイリアン ゲーム LSIゲーム : Toys & Games

I found what appear to be a few glitches in the Bandai Burgertime game: the first bug I found can be done by repeatedly pressing the down button while standing above the bottom bun on the first floor; this causes both the top and bottom burger buns to appear, completely eliminating the need to enter the top floor. 

The second bug occurs after beating 5 rounds, at which point the enemies and ladder barriers stop moving completely and don't respawn when eliminated. 

This effectively allows you to play the game indefinitely, which if you get beyond 19K points causes the score counter to break, though this appears to be a limit of the original unit being unable to display past that number correctly.

And this source appears to have a decent-quality scan of the Japanese box. (no idea why the text is big)

https://www.amazon.co.jp/-/en/m98805651865/dp/B0D87RM6T9

Here's a scan of the unit itself from https://page.auctions.yahoo.co.jp/jp/auction/f1087186355

I've got another potential suggestion for you today: this time it's a bit of a more unusual handheld; a model based on the arcade game of the same name, Heiankyo Alien.

Once again, I do not own this machine myself, but I do have an archive.org link that has the gameplay simulated already. I can try and look for scans of the unit, instructions and box if needed.

https://archive.org/details/hh_ghalien

If you have any other questions, by all means please ask away.

Sweet!!!

Of course. I've got some other game suggestions I intend on posting later, and with those there's actual emulated versions on Internet Archive or other places, so part of the work would already be done for you, I imagine. Merry christmas & happy holidays in advance!

Awesome! Here's some other videos I've found showing this game off that might be of some help to you.
https://www.youtube.com/watch?v=mXaf1jvPVdQ
https://www.youtube.com/watch?v=X-6kGoAmYjE
https://www.youtube.com/watch?v=wEqR6QBR_WM

Not really sure how to format these, so here goes; this is one of the most obscure handhelds I've actually seen in person, though I do not own it. It's based on the 1988 Namco arcade game of the same name and from what I can gather, it came out around the same time; you control Rick as you battle through three floors of monsters on a single-screen playfield in an attempt to save his girlfriend Jennifer. I've always found this game really fascinating for being an obscure entry in an already pretty niche series, though this does come at the cost of rarity & obscurity.

Below are some videos & articles about the game if this interests you:
West Mansion: The Splatterhouse Homepage - Splatterhouse: The LCD Handheld Game

I've been checking back on this website for many months now (maybe it's been over a year? I've lost track) and this is genuinely one of my favorite browser game pages on the internet; the accuracy is superb; the game selection is diverse and plentiful, and it goes a long way to preserve these often-forgotten pieces of gaming history which is always a good thing in my book!

Ever since the death of Flash and the subsequent loss of the french Pica Pic website, this is my favorite place to play these old handhelds online, and I cannot overstate how thankful I am of your hard work maintaining and adding stuff here. Cheers from Texas!