Demon Protocol

Update: Recent update added "bullet steering", which lets you take enemies out without risking the hail of bullets they keep coming and leave no breathing room. This changes a lot and makes the game playable. However, there are still some imajor ssues, like the fact you can't shoot through weapon power-up icons, while enemies have no such restriction and lead to cheap deaths, and difficulty spike after level 20 on hard mode that's impossible to handle. Generic shooter where you have to beat similar enemy waves across four stages, with every fifth stage featuring a boss fight. Altogether, there are 25 stages. You have three lives to beat the whole game, but there's barely any invincibility after dying, meaning you can die immediately after respawning, which becomes a cheap way to end your run in the later stages. While it’s possible to earn an extra life fairly quickly on normal difficulty, the points threshold goes much higher on high difficulty. Also, you can only have three lives maximum, so everything else goes to waste. There are no mechanics beyond moving around and holding your finger on the fire button. However, a string of silly design choices becomes increasingly annoy…

Old style arcade shooter with some interesting features like branching and guideable bullets. The attacks come fast and there is a boss battle after several waves. Normal mode was challenging for me I didn't try the harder difficulty settings. Has a co-op mode and works well with a controller or mouse/keyboard. Doesn't say if it works on Steam deck.