\documentclass[ngerman]{article}
\usepackage[T1]{fontenc}
\usepackage{babel}
\usepackage{csquotes}
\usepackage[
backend=biber,
citestyle=ext-authoryear,
bibstyle=ext-authortitle,
sorting=nyt,
maxbibnames=999, maxcitenames=2,
giveninits=true,
uniquename=init,
introcite=plain,
innamebeforetitle=true,
]{biblatex}
\renewcommand*{\newunitpunct}{\addcomma\space}
\DeclareNameAlias{sortname}{family-given}
\DeclareNameAlias{ineditor}{sortname}
\DeclareFieldFormat{editortype}{\mkbibparens{#1}}
\DeclareDelimFormat{editortypedelim}{\addspace}
\DeclareFieldAlias{translatortype}{editortype}
\DeclareDelimAlias{translatortypedelim}{editortypedelim}
\DeclareDelimFormat{multinamedelim}{\addslash}
\DeclareDelimFormat[bib]{multinamedelim}{\addcomma\space}
\DeclareDelimAlias{finalnamedelim}{multinamedelim}
\DeclareDelimFormat[bib]{nametitledelim}{\addcolon\space}
\DeclareFieldFormat*{title}{\mkbibemph{#1}}
\DeclareFieldFormat{journaltitle}{#1\isdot}
\DeclareFieldFormat{issuetitle}{#1}
\DeclareFieldFormat{maintitle}{#1}
\DeclareFieldFormat{booktitle}{#1}
\renewcommand{\locdatedelim}{\addspace}
\renewbibmacro{pubinstorg+location+date}[1]{%
\printlist{#1}%
\setunit{\publocdelim}%
\printlist{location}%
\setunit{\locdatedelim}%
\usebibmacro{date}%
\newunit}
\DefineBibliographyStrings{german}{
andothers = {et\addabbrvspace al\adddot},
}
\DeclareFieldFormat{bbx@introcite}{\mkbibbrackets{#1}}
\renewcommand*{\introcitepunct}{\par}
\DeclareOuterCiteDelims{parencite}{\bibopenbracket}{\bibclosebracket}
\addbibresource{biblatex-examples.bib}
\begin{document}
Lorem \autocite{sigfridsson,worman,companion,geer,westfahl:space,pines}
\printbibliography
\end{document}